Updating dependencies

I upgraded the project to use the latest version of GW2.NET, which comes with a number of breaking changes. This PR takes care of those changes, so you don't have to.

While I was at it, I also updated all other dependencies to their latest version.

Note: you have to upgrade your Awesomium SDK to the latest version (1.7.5): http://www.awesomium.com/downloads/awesomium_1_7_5b_sdk_win.exe

Some unit tests don't pass, but the ones that fail do not seem related to the changes that I made.