Refactor address addition/editing #3464

* Move creation of address to create_address method. The ability to add
  new addresses from edit_method will be deprecated from 3.2.x.
* A deprecation warning is shown where required.
* Make a helper function to manage contact mechanism in party.
* Add a new create-address URL.
Merge pull request #129 from sharoonthomas/develop

Refactor address addition/editing #3464