refactor(client): Move interTabCommunication out of fxa-client into the views that need it.

interTabCommunication crept into fxa-client. The interTabCommunication functionality is only really necessary in complete_reset_password, so it has been moved there.

fixes #1807
Merge pull request #1966 from mozilla/issue-1807-inter-tab-channel

refactor(client): Move interTabCommunication out of fxa-client into the views that need it.

rebased, thanks @zaach!

r=zaach