Add TravisLint pre-commit hook

Add pre-commit hook for checking Travis CI configuration files via the
`travis-lint` gem (https://github.com/travis-ci/travis-lint).

Change-Id: I3584eef11ffe12b1e8a339de531ec1d904842e29
Reviewed-on: http://gerrit.causes.com/36059
Tested-by: jenkins <jenkins@causes.com>
Reviewed-by: Shane da Silva <shane@causes.com>
Rename fail_check matcher to fail_hook

The name `fail_check` is a holdover from Overcommit pre-0.6.0. Change
the name to `fail_hook` to emphasize that it applies to the `Hook`
class (ideally we would just use `fail`, but that is a reserved word).

Also renamed the `CheckMatcher` class to `HookMatcher` and fixed a
Rubocop lint.

Change-Id: I25a5b9fb4ec37bbcb5026fed0810432e40eec7db
Reviewed-on: http://gerrit.causes.com/36060
Tested-by: jenkins <jenkins@causes.com>
Reviewed-by: Shane da Silva <shane@causes.com>