JBIDE-17062 - Cordova Download window

OK button is now disabled until a proper platform downlaod selection is
done. This commit also fixes JBIDE-17093 by capitalazing the column and
JBIDE-16988 by displaying an error message when version combo fails to
populate.
cleanup and improved error handling

Some code cleanup and improves a case where a thrown exception may have
been ignored.
JBIDE-17064 - Cordova Download wizard: complains Android SDK location is
not defined

AvailableCordovaEnginesSection starts to log precompilation errors as
warning and ignores them. This avoids the unncessary dialogs.