#204427 - Deadlock while adding Spring MVC framework into Maven Web Application

Bug:
http://netbeans.org/bugzilla/show_bug.cgi?id=204427

Description: When the maven customizers were generalized and fixed, 
there started to appear deadlocks by saving maven project customizer 
when some Web Framework was included. Deadlock is caused by creating new 
file under project mutex write lock. The way how to fix that was widely 
discussed in the issue and calling project extension in AWT EDT was 
considered as the safest solution.

Impact assessment: every first addition of Web framework into Maven 
based project finishes with deadlock

Risk assessment: changes are just maven.j2ee module related and it 
affects just the saving of customizer panels of this module, very low risk

The fix was reviewed by mjanicek and verified by jskrivanek.

Fix:
hg.netbeans.org/web-main/rev/f9f9e02059de

Thanks for the review,
Martin.