Fix #2251837; better response w/ security req'd. DO NOT MERGE

* Currently, we validate EAS accounts using a command that will
  succeed even if we do not support required security policies.
* This causes a confusing "invalid username or password" error
  when trying to sync with a validated account in the case that
  there are, in fact, required policies
* The fix is to send a sync command after validating the user name
  and password; a 403 error indicates the requirement for
  security policies.
* When we see the 403 error, we put up a message that is appropriate
  to the situation.

Change-Id: I74e132cb81f021cbb697cc9ee146405bf3ebc0ba
2 files changed