Merged source-list branch into master

Squashed commit of the following:

commit 874b5d1b9578d7cee0f40706410ea1e2ea0f0f95
Author: Dana Franklin <danaf@mediaartslab.com>
Date:   Wed Aug 7 15:07:29 2013 -0700

    Added brief descriptions of multi array controller and source list view

commit ba8fffcac9609c42a83952df890f68cdbaf87f22
Merge: 81d7201 0ceaf9b
Author: Dana Franklin <danaf@mediaartslab.com>
Date:   Wed Aug 7 12:52:37 2013 -0700

    Merge branch 'source-list' of github.com:realityendshere/emberella into source-list

commit 81d72013321a211ff548e4e3072a7bec50543d59
Author: Dana Franklin <danaf@mediaartslab.com>
Date:   Wed Aug 7 12:33:09 2013 -0700

    Made `arrangedContent` computation function length 2

commit 7f750a0b9a6d5c405516957c966287a621b853b9
Author: Dana Franklin <danaf@mediaartslab.com>
Date:   Mon Aug 5 15:53:50 2013 -0700

    Reduced selection change event triggering

commit d89aa49b47d77154bfe5ce4b77088650748a158f
Author: Dana Franklin <danaf@mediaartslab.com>
Date:   Mon Aug 5 12:55:06 2013 -0700

    Improved computation of "active" selection

    The "active" selection is typically the intersection of the current selection set and the current content array. That is, an item only appears actively selected when it is both in the selection set and the content.

    A new `getActiveContent` method for determining the content array from which active selections must be a member of was added to allow multi array controllers and the selectable mixin to work together.

commit 5345e2a4676ed845840bd7d187aeb934809f82d6
Author: Dana Franklin <danaf@mediaartslab.com>
Date:   Mon Aug 5 12:13:15 2013 -0700

    Added `getFlattenedContent` method to multi array controller

    Method flattens content across arrays/sub-arrays recursively to return a single array of items.

commit e6bbfcd1aa949366226c2a188d41aa40e262a499
Author: Dana Franklin <danaf@mediaartslab.com>
Date:   Mon Aug 5 12:09:22 2013 -0700

    Moved source list item template definition to item class

    Item view templates are no longer inherited from the containing source list view.

    This maintains consistency with Ember's built in collection views.

commit aa4d73ecac8d8dcd560b8edc34be39f36299d1ce
Author: Dana Franklin <danaf@mediaartslab.com>
Date:   Fri Aug 2 16:46:53 2013 -0700

    Added class to base source list; prevented element ID from being copied to child lists

commit 715e113be6f56713c5244a80c5432f9463dabfc6
Author: Dana Franklin <danaf@mediaartslab.com>
Date:   Fri Aug 2 16:26:39 2013 -0700

    Added emberella-source-collection class name

commit c88f3a8f20080b5119e382b0b2e1eec6f69a1f85
Author: Dana Franklin <danaf@mediaartslab.com>
Date:   Fri Aug 2 16:18:18 2013 -0700

    Refactored source list view to render heading independently of listing

    Added a bit of binding complexity… but...

    Duplicate headings are much more unlikely (if not impossible)

    Headings don't flicker when items are added to or removed from the list

    Added a computed property for finding the root source listing

commit 38fc34c51a4d3e6023534e85c2027de98312ddf5
Author: Dana Franklin <danaf@mediaartslab.com>
Date:   Thu Aug 1 21:14:37 2013 -0700

    Fixed a bug that would cause extra content to appear in multi arrays

commit be95f742105e0c8431ce26d0ce0251a2561df738
Author: Dana Franklin <danaf@mediaartslab.com>
Date:   Thu Aug 1 20:45:02 2013 -0700

    Added documentation (comments) and minor refactoring

commit 93ddad5e667ba1863a4be3c5317dc98cfe57f890
Author: Dana Franklin <danaf@mediaartslab.com>
Date:   Thu Aug 1 18:11:21 2013 -0700

    Created multi array controller and source list view

commit 0ceaf9b8fca253bdbbcd51d7755cdc2d8de9dc72
Author: Dana Franklin <danaf@mediaartslab.com>
Date:   Wed Aug 7 12:33:09 2013 -0700

    Made `arrangedContent` computation function length 2

commit b04d15227190acbb86489a3f4ec5b6d2ecf0193a
Author: Dana Franklin <danaf@mediaartslab.com>
Date:   Mon Aug 5 15:53:50 2013 -0700

    Reduced selection change event triggering

commit cb5d6a7a97387af6856d6621050d437d7e9d866b
Author: Dana Franklin <danaf@mediaartslab.com>
Date:   Mon Aug 5 12:55:06 2013 -0700

    Improved computation of "active" selection

    The "active" selection is typically the intersection of the current selection set and the current content array. That is, an item only appears actively selected when it is both in the selection set and the content.

    A new `getActiveContent` method for determining the content array from which active selections must be a member of was added to allow multi array controllers and the selectable mixin to work together.

commit 32b17fad9e7a8b8901b21bfb7f79138d76f19115
Author: Dana Franklin <danaf@mediaartslab.com>
Date:   Mon Aug 5 12:13:15 2013 -0700

    Added `getFlattenedContent` method to multi array controller

    Method flattens content across arrays/sub-arrays recursively to return a single array of items.

commit 5c00af8f95b20cdbdc2009527621d950cf7f67ec
Author: Dana Franklin <danaf@mediaartslab.com>
Date:   Mon Aug 5 12:09:22 2013 -0700

    Moved source list item template definition to item class

    Item view templates are no longer inherited from the containing source list view.

    This maintains consistency with Ember's built in collection views.

commit 3bc63cbf37e9462d2e964fcf306ab5fd3925d350
Author: Dana Franklin <danaf@mediaartslab.com>
Date:   Fri Aug 2 16:46:53 2013 -0700

    Added class to base source list; prevented element ID from being copied to child lists

commit 0fb02a8a6d91c26afc34a407df0f241a96d8788b
Author: Dana Franklin <danaf@mediaartslab.com>
Date:   Fri Aug 2 16:26:39 2013 -0700

    Added emberella-source-collection class name

commit 0a5a77c093175f72fac54b985d6372ad024584a4
Author: Dana Franklin <danaf@mediaartslab.com>
Date:   Fri Aug 2 16:18:18 2013 -0700

    Refactored source list view to render heading independently of listing

    Added a bit of binding complexity… but...

    Duplicate headings are much more unlikely (if not impossible)

    Headings don't flicker when items are added to or removed from the list

    Added a computed property for finding the root source listing

commit e2ce55897cda594b2b2846ab81ea5569a6f3854c
Author: Dana Franklin <danaf@mediaartslab.com>
Date:   Thu Aug 1 21:14:37 2013 -0700

    Fixed a bug that would cause extra content to appear in multi arrays

commit 627e53174378d6a17877b4c714b6b91b400686d4
Author: Dana Franklin <danaf@mediaartslab.com>
Date:   Thu Aug 1 20:45:02 2013 -0700

    Added documentation (comments) and minor refactoring

commit 74e8188e638ad9b5249c987c63914c6da3f54063
Author: Dana Franklin <danaf@mediaartslab.com>
Date:   Thu Aug 1 18:11:21 2013 -0700

    Created multi array controller and source list view