`try` allocates an array on every call, we should avoid calling it in
hotspots.  This reduced AttributeMethodsTest#test_setting_time_zone_aware_attribute_with_string
from 18k allocations to 14k

We tenderized the wrong method! Object#try already had the yield option, just needed some tenderloving instance_eval to fit the bill

Fixed Active Job Backburner adapter

This fixes random test failure in migrator_test.rb

Make test:isolated run without bundler for Action Mailer

Avoid skipping Sidekiq tests on Rubinius

Now that Travis provides support for Rubinius 2.2.10, we can run the
Sidekiq tests against this version.

Action Mailer tests weren't able to run in isolation without the bundle
exec prefix since we were requiring gems before requiring abstract_unit.

We don't need the `gem` call thus and the require_relative since the
test directory should be present in the load path when we run any test.

Asserting that the message contains "QUERY PLAN" is enough for the adapter's test.
The plan may vary according to number of tuples etc. but that's out of our concern.

[ActiveJob] extract JobBuffer from helper

This reverts commit 16fe1983, reversing
changes made to 4c81c8ce.

The call to `Model.reset_column_information` was to express the intent of the test.
`reset_column_information` itself can trigger SQL queries because it checks
for a tables existance. Let's move it outside of the block.

/cc @sgrif

[ci skip] Fix example code of ActiveRecord::FixtureSet.context_class

Don't rescue IPAddr::InvalidAddressError

IPAddr::InvalidAddressError does not exist in Ruby 1.9.3
and fails for JRuby in 1.9 mode.

As IPAddr::InvalidAddressError is a subclass of ArgumentError
(via IPAddr::Error) just rescuing ArgumentError is fine.

Fix the router ignoring constraints when used together with a redirect route

Using heredoc would enforce line wrapping to whatever column width we decided to
use in the code, making it difficult for the users to read on some consoles.

This does make the source code read slightly worse and a bit more error-prone,
but this seems like a fair price to pay since the primary purpose for these
messages are for the users to read and the code will not stick around for too
long.

[ci skip]

This test would fail when executed after any test that calls fixtures(:binaries)

There exists some other test files that load :minivans fixtures but don't load :speedometers.
Loading :speedometers here prevents the following error when this test was run after such test:
CalculationsTest#test_should_group_by_association_with_non_numeric_foreign_key:
ActiveRecord::RecordNotFound: Couldn't find all Speedometers with 'speedometer_id': (ABC, s1) (found 1 results, but was looking for 2)