Expose StagedFile#original_path

Some hooks need to operate on the staged file's original path, so we
need to make this property available for reading.

Change-Id: I93316b27331c8121a1468730462da4a380c37974
Reviewed-on: https://gerrit.causes.com/29833
Tested-by: jenkins <jenkins@causes.com>
Reviewed-by: Shane da Silva <shane@causes.com>
Update changelog and readme

A couple of commits were recently added without their respective
changelog entries. Likewise, a haml_style pre-commit plugin was added
but the list in the readme was not updated. This commit addresses both
of these issues.

Change-Id: I30cfa2d31aa85593aaae7fd77bdf46da9491d025
Reviewed-on: https://gerrit.causes.com/29834
Tested-by: jenkins <jenkins@causes.com>
Reviewed-by: Shane da Silva <shane@causes.com>
Add Gemfile.lock

This ensures that the dependencies don't change across installations of
the repo. Specifically, we hope that this will make sure that Travis CI
builds against the same dependencies that we are using locally.

Change-Id: I92b4a57ac09b2f14b29ace86d3c409754c933a23
Reviewed-on: https://gerrit.causes.com/29836
Tested-by: jenkins <jenkins@causes.com>
Reviewed-by: Shane da Silva <shane@causes.com>
Cut 0.3.0

Change-Id: I1ea696df079279e57aa1c34155ae7a50a686f177
Reviewed-on: https://gerrit.causes.com/29835
Tested-by: jenkins <jenkins@causes.com>
Reviewed-by: Shane da Silva <shane@causes.com>