Support to add the casting node to the AST at build time

Ref https://github.com/rails/arel/commit/93d72131bcc24ccb5536bec672d2dac94f8de651
Merge pull request #266 from yahonda/address_undefined_to_i_oracle

Support to add the casting node to the AST at build time to oracle
Make badges more consistent [skip ci]
Merge pull request #268 from arthurnn/readme_1

Make badges more consistent [skip ci]
Remove old FIXME comment

The comment was introducted on https://github.com/rails/arel/commit/d8de55cee197d887b478b134ec692776613bf998 , and the code has changed
Merge pull request #269 from arthurnn/remove_comm

Remove old FIXME comment
Added #update_manager and #delete_manager convenience methods for consistency
Return self from #distinct so it's chainable
convenience method for outer_join
Correct whitespace in README
Merge pull request #273 from adammw/patch-1

Correct whitespace in README
Merge pull request #267 from jordansexton/patch-1

Return self from distinct so it's chainable
Merge pull request #272 from jduff/rebased_outer_join

Add convenience #outer_join
Merge pull request #271 from jordansexton/patch-2

Added update and delete convenience methods