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
@demobox Did you mean it should NOT be linked with a relativePath?  The problem is that maven always looks at ../pom.xml first if there is no relativePath specified and spits out these:

```
[WARNING]
[WARNING] Some problems were encountered while building the effective model for org.apache.jclouds.cli:jclouds-cli-project:pom:1.8.1-SNAPSHOT
[WARNING] 'parent.relativePath' points at org.apache.jclouds.cli:jclouds-cli instead of org.apache.jclouds:jclouds-project, please verify your project structure @ line 23, column 11
```
Its a pet peeve of mine, but these can be silenced by adding <relativePath /> which basically tells it not to even try resolving locally. We already did this for the main jclouds projects, I was just throwing them in here while I was cleaning up. I can remove them if you want so just let me know.