bad sync server still saves the preference

If you enter a wrong sync server, you get an error message (after having merged lp:~tomdroid-dev/tomdroid/rework-auth-error-handling of course) but the preference is still saved.

I tried fixing it quickly but couldn't do so in satisfying way.

We can't simply prevent the preference update because we are running things in another thread and I couldn't figure out how to have the onPreferenceChangeListener be there to get the handler's response (or if I think it made sense for it to be there for that).

I also considered resetting the old value after receiving a failure but there's all sort of race conditions where the user's URL would be overwritten and it's just sloppy in my mind..

The real fix, which is intrusive enough to be done later and not in the 0.5.1 (or whatever we'll call it) cycle, is to get the OAUTH stuff done in it's own activity, pretty much like this guy do: https://gist.github.com/1009626

So, registering the bug because it exist. Anyone interested in implementing the fix: knock yourselves out! and let us know you are working on it.