OAK-840: Intermittent test failure for testRegisterNodeType on JDK 7

Use different node type names in separate tests since the test repository is shared across test cases and thus the ordering of tests could confuse a test with an already existing node type.

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1487869 13f79535-47bb-0310-9956-ffa450edef68