OAK-1896 - Move JR2 specific logic from oak-run to separate module

Modified the build to produce two jars
- oak-run - Contains all Oak related jars and supports all Oak modes
- oak-run-jr2 - Contains Oak and Jackrabbit 2 jars. Support all JR2 related modes like upgrade and benchmark

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1611742 13f79535-47bb-0310-9956-ffa450edef68