TRAVIS: quote colons which can trip up the yaml parser
TRAVIS: quote colons which can trip up the yaml parser

Putting a quote after colons fixes YAML parser syntax errors while
trying to match mappings. Syntax validated with:
  http://lint.travis-ci.org/

Signed-off-by: Tim Janik <6ec6ff229c4e1c5bbd5933ee92e6c5832ff023bb@gnu.org>

tim-janik/rapicorn,tim-janik/rapicorn,tim-janik/rapicorn,tim-janik/rapicorn,tim-janik/rapicorn