Update include paths
Switch to using test_util:{start,stop}_couch
Add .eunit to .gitignore
Switch to using config instead of couch_config
Delete tests for the no longer present couch_ref_counter.erl
Config set requires a value as a list, not a binary
WIP: Add test_util

The addition of start_config here is suboptimal, but starting couch
requires config to be running, and a number of the tests also want
config running, so this is a (temporary?) workaround to make sure you
can always get a fresh config instance.

Currently the request function is unused, but I think we should
migrate tests making requests to use it.
WIP: Switch to using test_util:start_config
WIP: Disable problematic tests