Upgrade MongoCSharpDriver package to v1.7

Hi Gian Marco,

would you please consider following contribution of mine.

Basically I wanted to upgrade the MongoDB C# Driver package to most recent (v1.7).
The reason is to avoid run-time conflicts for projects using both  MongoDB C# Driver and log4mongo packages.

I hope that commit messages are speaking for themselves:

* timestamp assertions made time-zone independent
* Upgrade MongoCSharpDriver package to v1.7
  - also enabled NuGet package restore
  - fixed few other project/package references

Please review my submission and don't hesitate to contact me if you have any questions further.

Cheers,
Igor