Bump java version, if allowed?

Change-Id: I69e3dde890fef13c31cf519523ce447a27ba29b9
Reviewed-on: http://gerrit.dmdirc.com/2701
Automatic-Compile: DMDirc Build Manager
Reviewed-by: Chris Smith <chris@dmdirc.com>

nbproject/project.properties

@@ -49,8 +49,8 @@ javac.compilerargs=
 javac.deprecation=true
 javac.processorpath=\
     ${javac.classpath}
-javac.source=1.6
-javac.target=1.6
+javac.source=1.7
+javac.target=1.7
 javac.test.classpath=\
     ${javac.classpath}:\
     ${build.classes.dir}