Use to_param instead of id method to route to a singular resource.
Update 3.0 active_admin.js
fix HABTM select filters

Assuming Foo HABTM Bars, the below now works as you'd expect:
```ruby
ActiveAdmin.register Foo do
  filter :bars
end
```
use the form buffer!
better filter defaults

+ `filter :attr, as: :select` now plucks DB values by default
+ properly add default polymorphic filters
+ move common Formtastic overrides into a single module
Merge pull request #1928 from Daxter/1093-dropdown-for-habtm

[1093] HABTM Select Filters
Feature dropdown for string filter to use contains, starts_with and ends_with #2002
Merge pull request #2096 from joseluistorres/2002-SQL-like-operate-on-text-field

Conflicts:
	lib/active_admin/filters/forms.rb
make the string filter logic a little clearer

`input_name_simple` is only ever called when the method already matches
a search condition so there's no need for it
Merge pull request #2212 from nicinabox/master

Fix 3.0 active_admin.js with jQuery 1.9
Merge pull request #2175 from cknoxrun/2173-router-should-use-to_param

Use to_param instead of id method to route to a singular resource.
Resolves #2173
don't build the table_tools div if it's empty

prevents an empty space from appearing above your table
Closes #2151 (kudos @clmntlxndr)