We were previously omitting cmaps meaning that
when signing documents with certain UTF-8 characters or CJK characters
they would appear as outlined squares in the pdf viewer despite the
actual pdf looking as expected with the characters displaying correctly.
This PR is handles the changes required to support envelopes. The new
envelope editor/signing page will be hidden during release.
The core changes here is to migrate the documents and templates model to
a centralized envelopes model.
Even though Documents and Templates are removed, from the user
perspective they will still exist as we remap envelopes to documents and
templates.
