#37 Prevent saving master project as xml format

[owb_support]

Niku Tracking Number 75527
Steps To Reproduce:
1. Open a master project from Clarity or the hard drive
2. Do File > Save As
3. Make sure you are pointing to the hard drive and not
Clarity
4. Change File Format to xml
5. Click Save
Expected: a message something like "Saving a master
project to an xml format is not a supported feature".
Actual: the file saves and looks ligitimate, but when you
try to open it in owb you get a blank project.