Updated buildnumber plugin

Buildnumber plugin 1.3 resolves Git branches correctly (http://jira.codehaus.org/browse/MBUILDNUM-66)
Merge pull request #22 from gastaldi/patch-1

Updated buildnumber plugin version
Remove apt plugin as it is deprecated in jdk7 and removed in JDK8
Update plugin version and add minimum maven requirement to 3.0.4 as newer plugins require it.