Twitter Demo: Access tokens NOT comitted on exit
Fixed bug which caused tokens to be NOT comitted on app exit

Any un-comitted chnages are 'synced' when a QSettings object
is destroyed. This happens in it's d'tor.

The bug was caused because the Helper class was created on
the heap w/o a parent. So on application exit, it's d'tor
was not getting called. This in turn prevented the QSettings
d'tor from being called and any un-comitted data in QSettings
was discarded.

Fix is to create the Helper on the stack for proper cleanup.

Bonus Fix:

The waitForMsg_ variable was not "value initalized". This
meant that it had garbage value stored in it. This meant that
sometimes, depending on its value, the slot
Helper::postStatusUpdate() would get called. Fix was to
explicitly initialize the boolean variable.