Reduce number of required OAuth permissions (server)

* Remove query of active user's email address in server script. This
  was not realy important and it was the only reason for two additional
  permissions that the user had to give to the Dontprint server script.
  Instead of detecting the active user's email address, send CC to a
  manually specified address, if requested by the user.

* Join the two Google API projects for the client and server side
  of Dontprint. Ideally, this should remove one of the two OAuth
  flows when running Dontprint for the first time. However, this
  only really works if the first call to a Google API already requests
  all required permissions. It is unclear what the correct scope
  is for App Script's "send email on behalf of the active user".
Delete file on Google Drive after sending email

When uploading a file, upload directly into trash folder. This eliminates
the need to put the file into trash from the server script. When email is
sent, delete the file on Google Drive for good with a "DELETE" API call.