Refactor logging to NLog and call the the fsharplex and fsharpyacc projects from the build task directly.

Using NLog to use it for exception logging during msbuild.
Finish off fsharplex integration.
Use FSharpYacc directly in the msbuild task.
Adjust targets file.
adjust error messages for fsharpyacc for msbuild intergration.
get tests to properly run with FAKE.
Improve output for unit test logging in FSharpYacc tests.
Adjust travis script to use fake.
Get rid of choose tags in fsproj files, because xbuild does not handle them correctly atm.