We should not include engine.rake file into rake

if we are passing -T which is skip_test_unit

See issue #6673 for more details.

I saw that we are not creating dummy app even if 
we do skip_test_unit. 

Fixes #6673
Merge pull request #6678 from arunagw/fix_issue_6673

Fix issue 6673
Don't add sqlite3 to gemspec with -O on rails plugin new

(closes #6672)
ActiveRecord#attributes optimization: minimize objects created
buffered logger is initialized with the log level passed trough the initializer
Duplicate tests removed.
Merge pull request #6689 from arunagw/duplicate_test_removed

Duplicate test removed
Merge pull request #6687 from tiegz/3-2-optimizations

ActiveRecord#attributes optimization: minimize objects created
fix namespace collision with test-unit-activesupport
Merge pull request #6693 from jkraemer/3-2-stable

Bugfix: Namespace collision with test-unit-activesupport 1.0.0
Merge pull request #6695 from kennyj/fix_6635

Fix #6635. We should call Scoping methods, before calling Array methods.
Merge pull request #6688 from c42engineering/buffered_logger_level_while_creation

BufferedLogger level while creation
Minimal change to query generation of exists? that makes SQLServer and others happy that do not work without a column alias.
Conflicts:
	activerecord/lib/active_record/relation/finder_methods.rb
Add test to column alias in `exists?` SQL.

This behavior was added in dd286a4c735dac1db8c9262581c7f29c44d1f695

Closes #1139.

Fixes #2553, #1141, #1623 and #2062.
Remove warning
Merge pull request #6521 from Empact/throw-result

Fix that #exists? can blow up with ThrowResult exception
Conflicts:
	activerecord/lib/active_record/relation/finder_methods.rb
Merge pull request #6698 from yahonda/address_ora_911_master

Address ORA-00911 errors because of the heading underscore.
Merge pull request #6690 from suginoy/fix-templates-copy

Fix: 'rake rails:templates:copy' doesn't work
Conflicts:
	railties/test/application/rake_test.rb
Fix GH #3163. Should quote database on mysql/mysql2.

Conflicts:

	activerecord/test/cases/adapters/mysql/mysql_adapter_test.rb
Change the string to use in  test case.

Conflicts:

	activerecord/test/cases/adapters/mysql/mysql_adapter_test.rb
	activerecord/test/cases/adapters/mysql2/schema_test.rb