Clean up mailgun.go
go fmt
Add messages.go docs
Add more godocs to messages.go
Add acceptance tests for messages
Fix type error in DNS structure, add godocs
Add domains acceptance tests.
Add godocs for domain API.  Fix type error.
Merge branch 'godoc-cleanup' into create-acceptance-tests

Conflicts:
	domains.go
Amend send acceptance tests with support scenarios
Fix authentication bug
Add test to get spam complaints
remove debugging code
Add get specific comaplaint test
Add bounces tests.
Add specific test for code example purposes
Make timestamp to GetStats optional.
Forgot stats.go in previous commit
Add acceptance tests for GetStats and friends
Add godocs