Added test to ensure that DescendantsTracker does not leak memory on singleton classes
Change ActionController::Parameters#require behavior when value is empty
When the value for the required key is empty an ActionController::ParameterMissing is raised which gets caught by ActionController::Base and turned into a 400 Bad Request reply with a message in the body saying the key is missing, which is misleading.

With these changes, ActionController::EmptyParameter will be raised which ActionController::Base will catch and turn into a 400 Bad Request reply with a message in the body saying the key value is empty.
asset guide, match application.rb snippets to the generated file [ci skip]

`if defined?(Bundler)` is no longer used in our current application.rb
fix HashWithIndifferentAccess#to_hash behaviour
Updates to make rails 4 happy with minitest 5:

+ Namespace changes, overhaul of runners.
+ Internal ivar name changes
- Removed a logger globally applied to tests that spew everywhere?!?
+ Override Minitest#__run to sort tests by name.
+ Reworked testing isolation to work with the new cleaner architecture.
- Removed a bunch of tests that just test minitest straight up. I think these changes were all merged to minitest 4 a long time ago.
- Minor report output differences.
Fixed a bug in  when using has_many association with :inverse_of option and UUID primary key.
cleanup, switch arguments in assert_equal calls
cleanup, assert on warning from postgres adapter
tweak dependencies
oops. I should have only required minitest, not minitets/autorun. muscle memory.
Remove unnecessary require from active_support/inflector/methods.rb

`active_support/inflections` already requires
`active_support/inflector/inflections`. There's no need to require it in
`active_support/inflector/methods`.
conditions in callbacks return consistent lambdas
wrap all options in lambas
using lambas for the callback bodies
fix method names
remove dead code
callbacks are wrapped with lambdas
make_lambda is never called with an Array
no need for variable assignments, just pass the values in
callback sequence is no longer used