MainPage.xaml.h

- fix : upon creation of 2+ accounts, the blockchain name appears
  as registerable regardless of check.
- fix : after having already created account without registering
  a blockchain name, editing the account to add a blockchain name
  succeeds but does not return to user to the UI from the loading
  page.
- fix : editing account details more than once, does not return
  the user to the UI.
- fix : click to accept modification for an account without any
  data changed result to wrong behaviour.

Change-Id: I08f19e6c902070b6260c466670badf3eab606934
Tuleap: #790