Feature/fix json dot notation

There was a problem with dots in json keys: the c# api uses a dot notation to describe the path to an element, this causes a problem when a key has a dot. 

A fix was made to allow dots in keys, by escaping them (when used in this dot notation). The escaped dot is not valid json, so is unambiguous, when escaping valid json.  

The change should not change the behaviour in cases when the old way worked. Unit tests where added to check the fix, and to check that it does not break anything.

see: https://jiradatasift.atlassian.net/browse/ALT-28