Functional test for GRAILS-9810.

I have updated the content negotiation functional test to check that Grails
correctly handles an accept header and returns the appropriate content type.
Enable accept header parsing for content negotiation tests.

It seems that GRAILS-9810 is a non-issue. It's simply down to a missing
configuration option that happens to be undocumented.
ignore .swp files
GRAILS-8991 - test binding String to Set<Integer>
Merge branch '2.1.x' into 2.2.x