Maemo: Create dedicated plugin.

No change in functionality for now. More support for generic remote
Linux support is planned to be added.

The changes in decreasing order of magnitude:
1) Move contents of qt4projectmanager/qt-maemo to new "RemoteLinux" plugin.
2) Make some classes in qt4nodes public for now. More decoupling
in that area will follow.
3) Fix some minor problems uncovered by the move.

Change-Id: I51d0c7977c10019eb6080cd6620bc28ecebad3c4
Reviewed-on: http://codereview.qt.nokia.com/106


Reviewed-by: Daniel Teske <daniel.teske@nokia.com>