document habtm join-table name with custom prefix [ci skip].

Closes #9643.

The logic was introduced with 46492949
Merge pull request #9645 from senny/9643_habtm_wrong_table_name

document habtm join-table name with custom prefix [ci skip]
Address ActiveRecord::StatementInvalid: OCIError: ORA-00979
Change from each to each_value on hash to avoid unused variable warning
Merge pull request #9650 from yahonda/group_by_oracle

Address ActiveRecord::StatementInvalid: OCIError: ORA-00979
Merge pull request #9651 from vipulnsward/change_to_each_value_intest

Change from each to each_value on hash to avoid unused variable warning
Fixed tests for returning an instance of `Time` in the local system timezone.
Merge pull request #9653 from jetthoughts/master

Fixed tests `to_time` returning an instance of `Time` in the local system timezone.

Tests for to_time returning an instance of Time in the local system timezone did not take in account DST when they used mixed timezone declarations like 'US/Eastern' and '-0500'.

Replaced timezone with DST by timezone without DST.
Cleanup tests for unused variables
add an missing assertion to inheritance_test.rb

assertion for
https://github.com/rails/rails/blob/ad624345e54bd20802de67b2b5c9ef29ecf5
d5f4/activerecord/lib/active_record/inheritance.rb#L32
Merge pull request #9658 from tkhr/add-assert-to-test_company_descends_from_active_record

add an missing assertion to inheritance_test.rb
Merge pull request #9657 from vipulnsward/cleanup_tests

Cleanup tests for unused variables
I think "uniq" is more Rails-y than select("distinct(categories.id)")
Merge pull request #9080 from sikachu/master-rails-test

Add `rails test` command to run the test suite
Fix test failure introduced in 3ed41e57

I forgot to run the test suit after changing the task name. :bomb:
Merge pull request #9664 from sikachu/master-fix-test_test_failure

Fix test failure introduced in 3ed41e57
debugger does not work on trunk
default the reaping frequency to 10 seconds
Mention that debugging can be slow.

https://github.com/rails/rails/pull/3180\#issuecomment-14705821 has
mention of rendering going from 1-2ms to 4 seconds with this on,
which seems reasonable: debugging is slow.
Make sure that the test case is run under test env

* Unset $RAILS_ENV that got set by abstract_unit to trigger the default.
* split out environment setting since Ruby 1.9.3 doesn't support inline
  ENV setting.