Task/mongo check version geo

Adding version check for geo-queries.

Now, when running unit test against MongoDB 2.2, the CB doesn't explode with assertion errors, it only makes geo query unit tests fail (and only those unit tests, all the other unit tests and harness tests work), reporting the following in /tmp/unitTestLog:

```
W:Thursday 06 Mar 17:09:32 2014(710):test/unittests/unitTest-/MongoGlobal.cpp[497](p.928)(t.928) processAreaScope: location scope was found but your MongoDB version doesn't support it. Please upgrade MongoDB server to 2.4
```