Added jquery-ui-rails as a dependency

Conflicts:
	activeadmin.gemspec

undoes 1d29474c489d558, to apply the full fix
limit support to Rails >= 3.2 and Ruby >= 1.9

#### Removed outdated version-checking conditions
Modules affected:
+ CSV parser
+ asset registration
+ class reloading in development

#### Removed 99% of our custom class reloader in favor of Rails reloading
Note: I removed the code that purges `app/admin` from Rails' `eager_load_paths`
since there were no bad effects of doing so. Only the code that does this for
Rails' `autoload_paths` seems necessary.

#### Gemspec dependencies updated
+ fastercsv removed
+ coffee-rails added
+ sass replaced by sass-rails
Strong Parameters support for Rails 4

Adds conditionals to the admin user generator, and to the AA Comments
model & controller to handle both Protected Attributes and Strong Paramaters

Also updates dependencies so the test Rails 4 app will at least bundle
move from Metasearch to Ransack

Note that while Ransack renames many query methods ("predicates"), this
commit creates aliases for the more plain-english predicates so they
still work as expected.

To see the full list of Ransack predicates, check out
`lib/ransack/constants.rb` in the Ransack source code.

This commit also removes polymorphic foreign types from the default
list of filters for a resource, since Ransack seems to barf on them. We
don't have a good filter UI for them anyway, so it's not a huge issue.