Don't specify language in .travis.yml

Travis CI has started their rollout of the Trusty Linux distribution. For some reason when that distribution is used and the language is specified as bash the xvfb virtual display configuration fails, causing the build to later fail when an attempt to run arduino is made. In this usage there really is not a valid language to set and not specifying any language solves the problem so I think this is the best solution.

Author: per1234

.travis.yml

@@ -1,6 +1,5 @@
 # This file is used to test the script with Travis CI
 
-language: bash
 # Although sudo is no longer required by arduino-ci-script since the 1.0.0 release, for some reason setting "sudo: false" causes the Travis CI build time to significantly increase so this setting is left as "sudo: required"
 sudo: required