ISPN-3654 Update to Infinispan 7.0.0.Alpha1

Hi!

Please take a look at proposed solution for https://issues.jboss.org/browse/ISPN-3654.

Changes:
* Updated to current Infinispan version
* Changed JDK compiler version to 1.7 (1.6 is out of life)
* Removed unnecessary compiler plugin (not required since Maven 3.0.4)
* Updated the code
* Added necessary repos to the settings.xml

Best regards
Sebastian