Putting authentication in a fragment was a problem, it
means that we need fragments as children of other fragments.
While this works in theory, it adds a lot of complexity.
Now, authentication is done with AuthenticationView,
which is just an extension of LinearLayout.
Currently, this does not yet handle adding certificates
for exchange accounts, but I'll fix that ASAP. As it is,
this is better than the current state, which crashes on
account setup 100% of the time.
Change-Id: I4274e7250f97012c3dc476003fd36fb960f2b728
