CI for Fake building on Windows and Mono

Made changes for Fake make file to work on mono.
However there are problems running Nunit tests for some unknown reason.
example: https://travis-ci.org/jbtule/FsUnit

Verified Fake still works on windows, still passes all tests
example: https://ci-beta.appveyor.com/project/jbtule/fsunit

MBUnit gallio.echo.exe not in nuget package as referenced, removed line in Test target since test runner doesn't exist.

CI configs are checked into repository, you'd only need to sign up for each free service and point them to the repo if you take this PR.