* cleanup: go vet and golint run
Various cleanups trickered by go vet and golint.
* Fix tests and lowercase all errors
Lowercase all errors, some tests in kubernetes use errors from
kubernetes which do start with a capital letter.
* middleware/file: don't reload zone when SOA isn't changed
Give Parse an extra argument which is the SOA's serial, if > 0 we check
against the just parsed SOA and then just return.
Most notable use is in reload.go which is both used in the file and auto
middleware.
Fixes#415
* PR comments