Gemfile for bundler, nuget and library updates

This pull is a enjoy weekend pull ;) It contains the gemfile which allows to do:

```bundle install``` 

in the checked out folder. This automatically install rake, albacore, zip and nuget (awesome) on the machine.

With the newest version of nuget the targets file is no longer needed. VS does an automatic restore. The rake script ensures a restore when not using VS.

Some library updates.

Remark: When you pull this in make sure that you execute bundle install in the agent checked out folder before invoking the rake scripts. This will ensure that everything is on the agent. If you need help you know where to reach me ;)

Have a nice weekend