Improve NetBeans .gitignore rules

According to this (http://netbeans.org/kb/docs/java/import-eclipse.html#versioning) knowledge base article, the nbproject folder should be checked into the VCS in order to allow people to open the project without importing.

Global/NetBeans.gitignore

-nbproject/
+nbproject/private/
+build/
+nbbuild/
+dist/
+nbdist/
 nbactions.xml