treat empty github token like missing github token
Deal with the case where unrecognized string is given in `language`

You can find strange values in users' config files.
Fall back to the default language if `language` is not recognzied
Do not modify the object in place

It may be used elsewhere we don't know of
Expand 'jdk' for Scala projects
Merge pull request #311 from travis-ci/ha-bug-scala_matrix_expansion_on_jdk

Expand 'jdk' for Scala projects
Fix rejected pushes in receive service

Previously there was no way to reject pushes based on a payload. After
introducing build_pushes setting it's now possible and receive service
code was not updated for such a possibility
Allow to set repository_filter rules as strings

Currently rules for repository_filter are hardcoded in config.rb, but
there is no way to put them in config. This change allows to set rule in
config and avoid bumping travis-core when changing the rule.
Merge pull request #310 from travis-ci/ha-bug-unrecognized_language

Deal with the case where unrecognized string is given in `language`
Merge pull request #305 from travis-ci/rkh-empty-github-token

treat empty github token like missing github token
Merge branch 'master' into ha-feature-multi_os_support