Removing branch command.

So it turns out the method to create a changeset from the API isn't
available in gerrit 2.8.1

Change-Id: I3f22ebde74a97be54ed5a80a7cd2c6c9bdb8a0d9
Merge remote-tracking branch 'commnerd/go' into go
Moving ChangeInfo out to a changes.go file.

Universal items for working with the changes endopoint go go here.

Change-Id: Ibe5a6fcaca0e8f8fbd55ef4aa3e5116535449f31