* Numerous classes modified to deal with this change
* Fixes bugs 1993292 and 1994671
* Renamed various setter and getter methods to reflect the underlying
field names
* Renamed syncFrequency to syncInterval in Account and Mailbox
* Convenience method added to AccountSettings to save only user settings
* Calls to content.update(context, content.toContentValues()), which save
all fields, should be double-checked for correctness, making sure that
content has current data and will not conflict with other threads that
might modify that data
* Ran all unit tests to confirm proper function
NOTE: The logic to enforce single default account no longer works,
because that logic is in Account.save() and does not run via
Account.update(). I have patched out a small section of the relevant unit
test and will file a bug to come back for this fix.
