Bump scala version to 2.11
Better handling of accept headers

This fixes a compiler warning due to a non-exhaustive pattern match.
Also, the q parameter is set to default to 1.0f if the toFloat fails
insted of throwing an exception. An appropriate test case has also been
added.
Merge pull request #29 from vikraman/2.11

Switch to Scala 2.11 and a small fix