ZOOKEEPER-3230: Add Apache NetBeans Maven project files to .gitignore
Author: Enrico Olivelli <eolivelli@apache.org>
Reviewers: phunt@apache.org
Closes #746 from eolivelli/ZOOKEEPER-3230-netbeans-maven-gitignore
Change-Id: Ifd31386069a867293d21825239a38c4f8c38b3f1