Fixed the batch actions drop down menu for nested tables
refactor applicaiton.rb
update all rails versions in the test suite

For #2005

This fixes a problem encountered by anyone who had generated their
`spec/rails` test environment (occurs on first run) after #1970 was
applied. The problem was that I had updated only a few places where we
refer to the current Rails version to be tested. This commit changes
all of them, as well as bumps 3.2 and 3.1 to reflect the new release.

If you ran into the #2005 problem, please run these steps:
```ruby
rm Gemfile.lock
bundle
rm -rf spec/rails/
rspec spec
```
consolidate Rails versions to the Travis config file

Now everything depends on `.travis.yml`. If that updates, so to does
the manually-run test suite.
Merge pull request #2006 from Daxter/bugfix/update-all-the-rails

[2005] Update all the Rails!
Merge pull request #2007 from fd/master

Position the dropdown menu relative to the next positioned parent instead of the document.
keep `remove_filter` from hitting the database

Now any calls to it are cached until render time :heart:
update to #2006; better file lookup

This uses the same convention as `RAILS_VERSION_FILE` for more consistent lookup.
Specifically, #2006 broke `./script/local server`.
Merge pull request #2014 from Daxter/bugfix/1876-lazy-filter-removal

[1876] Make `remove_filter` lazy
always return a string from `with_new_form_buffer`

fixes `semantic_errors` regression from #1996 as per
my discussion with @coreyward in the diff for a1cfdb69d7ad
fix jQuery 1.9 compatibility issue

As per this discussion:
https://github.com/gregbell/active_admin/pull/1879#discussion_r3453478
cleanup

this is a general refactor, and doesn't change behaviour
Merge pull request #2016 from Daxter/refactor/js

JS Refactor
fixes regression from #2014

closes #2020
Use Rails' url helper in devise.rb's root_path.

This fixes #1791.
dynamic scope names

You can now pass in a proc as the first argument to a scope and
have that rendered on your index page.
Merge pull request #2018 from Daxter/feature/dynamic-scope-name

Dynamic scope names
don't translate the string used for f.has_many javascript
Merge pull request #2030 from Daxter/bugfix/1832-has_many-js

[1832] Don't translate the model name for `has_many` JavaScript
Fix for issue #2033 - modify the default "delete" batch action to redirect to the collection path via route_collection_path to ensure that the path will work for nested (belongs_to) resources.