NEW PROVIDER: OctoDNS (#309)

* govendor gopkg.in/yaml.v2
* Ignore YAML and BIND test data litter.  Create README.txt files to force git to create subdirectories.
* Update convertzone to also read OctoDNS files

models/t_mx.go

@@ -17,7 +17,6 @@ func (rc *RecordConfig) SetTargetMX(pref uint16, target string) error {
 	if rc.Type != "MX" {
 		panic("assertion failed: SetTargetMX called when .Type is not MX")
 	}
-
 	return nil
 }