Update karaf version to latest 2.3.6

Hopefully fixing:
https://issues.apache.org/jira/browse/JCLOUDS-673
https://issues.apache.org/jira/browse/JCLOUDS-674
> Did you mean it should NOT be linked with a relativePath?

Ah, OK, if those warnings are appearing I might have had an incorrect understanding of this. I was going by the description in the [POM reference](http://maven.apache.org/pom.html):

"Notice the relativePath element. It is not required, but may be used as a signifier to Maven to first search the path given for this project’s parent, before searching the local and then remote repositories."

I was assuming that Maven would check the local and remote repos if a relative path was **not** specified, and that those warnings only appeared when the relative path **was** specified but pointed at the wrong thing.

If we get these warnings **without** a relative path and `<relativePath />` is the way to get rid of them (which seems a bit odd, but it would hardly be the only odd thing about Maven ;-) ), then I'm all for it.

Thanks for explaining!