TokencodeBackend: Stop updating if onPause() is called from the update function

TokencodeWidgetService.onTokencodeUpdate() will call onPause() if there is
no more work left to do.  onPause() cancels all scheduled work on mHandler
but doUpdate() promptly schedules a new work item after
onTokencodeUpdate() returns, which is wrong.  Check for this condition.

Signed-off-by: Kevin Cernekee <cernekee@gmail.com>
ImportActivity: Always confirm token import

Importing from an email client can be somewhat disconcerting, as tokens
with no devid/password will be silently accepted with no user interaction.
Then if the user clicks on the token again, he will be prompted to
overwrite the "old" token (which he just imported) with the same "new"
token.

So, let's display ImportConfirmFragment unconditionally.  For new tokens
the verbiage will be slightly different, but at least it will provide
a clear way to accept/decline the new token.

Signed-off-by: Kevin Cernekee <cernekee@gmail.com>
Update changelog and bump version to 0.81-pre (810)

Signed-off-by: Kevin Cernekee <cernekee@gmail.com>
Update changelog and bump version to v0.81 (819)

Signed-off-by: Kevin Cernekee <cernekee@gmail.com>