removed the branches endpoint

we already have branch info accessible via the repos endpoints, having this at the root level doesn't make sense.
Bump travis-core (for fixing the settings specs)
Merge pull request #94 from travis-ci/jk_remove_branches_endpoint

Remove the branches endpoint
regenerate gemspec
add endpoint for linting
Merge pull request #123 from travis-ci/rkh-lint

add endpoint for .travis.yml linting
Revert "removed the branches endpoint"

This reverts commit f7450cdb6b195e5220b6568f2fbf07db88171dd0.
enable bundler caching