Upgrading Bouncy Castle to 1.49 (1.50 has issues with OSGi)

Artifact ID has also changed: bcprov-jdk16 -> bcprov-ext-jdk15on

See https://github.com/jclouds/jclouds-karaf/pull/29 and [JCLOUDS-440](https://issues.apache.org/jira/browse/JCLOUDS-440)