Fix Rspec deprecation warnings when running test suite
Update wording for authorization in README

Quick update for clarification. Tripped me up for a few minutes.
Add constants for case insensitive searching
Patch Arel to give the search logic
Merge pull request #402 from OhaiBBQ/patch-1

Update wording for authorization in README
Allow flexibility of "or" grouping on base search
Added test for sending "or" base grouping
Make true and false predicates accept false values

This will make all boolean predicates more consistent.
Avoid order indication in separate line in sort_link.
Merge pull request #406 from markedmondson/or-grouping

Allow flexibility of "or" grouping on base search
Clean up search_spec.rb and move new test

Follow-up to #406
Context does not reference search
Merge pull request #411 from avit/cleanup-context-attr

Context does not reference search.
Merge branch 'master' of https://github.com/activerecord-hackery/ransack
Merge pull request #410 from nagyt234/use-nbsp-in-sort_link

Avoid order indication in separate line in sort_link.
Merge branch 'master' of https://github.com/activerecord-hackery/ransack
Freeze/DRY form_helper strings
Support merging joins across searches using a shared context

When merging search criteria, it's necessary to use the same join
dependency with a shared alias tracker. This can be achieved by passing
a context option when building Search objects.

Rails 3.0: use Model.joins(context.join_associations) to merge relations
with JoinAssociations.

Since Rails 3.1: can use Model.joins(context.join_sources) to merge
relations with Arel::Join nodes.

Since Rails 4.1: only context.join_sources is available as Arel,
context.join_associations stops being supported.
Merge pull request #412 from avit/shared-context

Support merging searches using shared context
Update README regarding changed I18n in Rails 4.2

[skip ci]