Update maven war plugin

Release notes: http://mail-archives.apache.org/mod_mbox/maven-announce/201307.mbox/%3CCAPoyBqQK_xpD73WD4nRfccvzUVoXuZW5DmNxAKomOjyBnLvG2w@mail.gmail.com%3E

Resolves a lot of Eclipse Juno Maven integration issues.