You're missing out on a couple of things here.
- Since this post is related to AS7, the correct forum is actually https://community.jboss.org/en/jbossas7/dev
- You forgot the plugin repository for Maven. Make sure that you configure the <pluginRepositories/> within your xml configuration. See the 'Configuring Maven to use the JBoss Repository' on: https://community.jboss.org/wiki/MavenGettingStarted-Users
- I wouldn't call Maven directly from the command line in the directory you've checked out. There are some intricacies to the build process, so I always run the build.sh (build.bat for Windows) for the compilation to work.
If this isn't enough, please post up on the correct forum - I don't want to be spamming the JBoss Tools forum.