WSAPI CHANGES: All server responses are now objects, makes some funky browsers...

WSAPI CHANGES: All server responses are now objects, makes some funky browsers happy and prevents certain attacks.  closes #217 closes #325

  * /wsapi/have_email now returns { email_known: <boolean> }
  * /wsapi/stage_user now returns { success: <boolean> }
  * /wsapi/user_creation_status now returns { status: <string> }
  * /wsapi/complete_user_creation now returns { status: <boolean> }
  * /wsapi/stage_email now returns { success: <boolean> }
  * /wsapi/email_addition_status now returns { success: <boolean> }
  * /wsapi/complete_email_addition now returns { success: <boolean> }
  * /wsapi/authenticate_user now returns { success: <boolean> }
  * /wsapi/remove_email now returns { success: <boolean> }
  * /wsapi/account_cancel now returns { success: <boolean> }
  * /wsapi/logout now returns { success: <boolean> }

Finally, introduced middleware to ensure that resp.json() is not called with anything other than an object.