Improved generation of credits box

 - Removes duplication from generation of credits box content
 - Donot generate copyright and imprint links without target or label
Merge pull request #99 from g-w/gw-imprint-copyright-links

Improved generation of credits box
rescue ActionController::UnknownFormat

refs #90

respond with 404 instead 500.
Merge pull request #101 from tf/unknown-format

rescue ActionController::UnknownFormat
Fix Configuration Duplication on Page Creation

Turn pageflow.Page#defaults into a function. Otherwise new pages share
the same object as their configuration attribute causing modification
of the default page configuration when page is edited.
useFakeXhr js spec support helper
extract ChapterPagesCollection from Chapter model

extend SubsetCollection to mix in orderedCollection instead of mixing
it into SubsetCollection itself.
do not save order of empty collection

refs #90

rails does not like when ids is empty array.
do not save order on receive

refs #90

update is hook is called anyway afterwards. prevent duplicate order
request which might related to MySQL dead lock errors.
consolidate positions in ordered collection on remove

removing an item at the top and adding a new item caused duplicate
position attributes.
sort files by lowercase file names

fixes #86

otherwise lowercase files come last.
Merge pull request #103 from tf/dup-page

Fix Configuration Duplication on Page Creation
Merge pull request #105 from tf/files-order

Sort Files by Lowercase File Names
Merge pull request #104 from tf/sorting

Improve Sorting Chapters and Pages
Local Variable `entry` for `published_entries_exhausted` Partial
Improve Sorting in Membership Form

* Display and order users by "last_name, first_name"
* Order entries by title
* Move helpers into `Admin` module
Merge pull request #106 from tf/publish-exhausted-entry-var

Local Variable `entry` for `published_entries_exhausted` Partial
Merge pull request #107 from tf/membership-form-order

Improve Sorting in Membership Form
CSS fixes in default theme

* Remove margin from link
* Fix link dialog in rich text editor
Merge pull request #108 from tf/anchor-margin

CSS fixes in default theme