OPENDJ-808 Implement a simple commons REST based HTTP connection handler

Made the code compile with java 6 until we can further solve the issue.
I'll come back to this code to uncomment the lines I commented here.

ivy.xml:
Excluded the dependency to activation.jar.
Remporarily downgraded grizzly and javax.servlet versions.
Replaced tabs with spaces.

HTTPConnectionHandler.java:
Commented out some code to be reenabled in a subsequent commit.