Configure Travis for better build performance
Configure Travis for better build performance

* set sudo: false to allow usage of their new container-based
  infrastructure
* enable bundler caching

Change-Id: I5527d446e40688d2b564244c57883c4837dad77b
Reviewed-on: http://gerrit.causes.com/45436
Tested-by: jenkins <d95b56ce41a2e1ac4cecdd398defd7414407cc08@brigade.com>
Reviewed-by: Shane da Silva <67fb7bfe39f841b16a1f86d3928acc568d12c716@brigade.com>

artemartemov/scss-lint-hdm