Add missing dependencies on cassandra driver module

The module org.hawkular.commons.cassandra-driver is missing the following dependency:

<module name="javax.api" />

Giving some blocker errors like:

2015-12-18 08:50:17,237 ERROR [stderr] (Thread-0 (ActiveMQ-client-global-threads-602174853)) Caused by: java.lang.ClassNotFoundException: javax.management.InstanceNotFoundException from [Module "org.hawkular.commons.cassandra-driver:main" from local module loader @14899482 (finder: local module finder @21588809 (roots: /opt/git/hawkular-alerts/hawkular-alerts-rest-tests/target/hawkular-alerts-rest-tests-0.8.0.Final-SNAPSHOT/modules,/opt/git/hawkular-alerts/hawkular-alerts-rest-tests/target/hawkular-alerts-rest-tests-0.8.0.Final-SNAPSHOT/modules/system/layers/base))]
2015-12-18 08:50:17,237 ERROR [stderr] (Thread-0 (ActiveMQ-client-global-threads-602174853)) at org.jboss.modules.ModuleClassLoader.findClass(ModuleClassLoader.java:205)
2015-12-18 08:50:17,238 ERROR [stderr] (Thread-0 (ActiveMQ-client-global-threads-602174853)) at org.jboss.modules.ConcurrentClassLoader.performLoadClassUnchecked(ConcurrentClassLoader.java:455)
2015-12-18 08:50:17,238 ERROR [stderr] (Thread-0 (ActiveMQ-client-global-threads-602174853)) at org.jboss.modules.ConcurrentClassLoader.performLoadClassChecked(ConcurrentClassLoader.java:404)
2015-12-18 08:50:17,243 ERROR [stderr] (Thread-0 (ActiveMQ-client-global-threads-602174853)) at org.jboss.modules.ConcurrentClassLoader.performLoadClass(ConcurrentClassLoader.java:385)
2015-12-18 08:50:17,243 ERROR [stderr] (Thread-0 (ActiveMQ-client-global-threads-602174853)) at org.jboss.modules.ConcurrentClassLoader.loadClass(ConcurrentClassLoader.java:130)
2015-12-18 08:50:17,244 ERROR [stderr] (Thread-0 (ActiveMQ-client-global-threads-602174853)) ... 176 more

So, in order to use the module this dependency needs to be added.