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.
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