Move over Squirrel.Client code, fix it all up except for UpdateManager
Rewrite UpdateManager

* Remove Filesystem Abstractions
* Rx => async/await
* Nuke the AppDomain stuff
Just use the Log() method
Make all the tests pass by deleting the ones I don't like
Add test files, update namespaces
Merge remote-tracking branch 'origin/master' into resurrect-client
Comment out a ton of tests and fix up the rest to build
Make package application sync for now
Pour some await on these tests
Comment out more tests
Merge pull request #7 from Squirrel/resurrect-client

Resurrect UpdateManager