Rails4 merges master branch

This pull request merges commits done in master branch into rails4 branch.

```ruby

$ git checkout rails4
Already on 'rails4'
$ git checkout -b rails4_merges_master_4th
Switched to a new branch 'rails4_merges_master_4th'
$ git merge mastert
Auto-merging Gemfile
CONFLICT (content): Merge conflict in Gemfile
Auto-merging activerecord-oracle_enhanced-adapter.gemspec
Auto-merging lib/active_record/connection_adapters/oracle_enhanced_adapter.rb
Auto-merging lib/active_record/connection_adapters/oracle_enhanced_schema_statements.rb
CONFLICT (content): Merge conflict in lib/active_record/connection_adapters/oracle_enhanced_schema_statements.rb
Auto-merging spec/active_record/connection_adapters/oracle_enhanced_schema_statements_spec.rb
Automatic merge failed; fix conflicts and then commit the result.
$
```

These two conflicts are resolved.