Propogate additional compilation data from RoslynCompilationService

* Update CompilationFailedException to include path of file being compiled
* Pass in path being compiled to Rolsyn.
* Adding doc comments for compilation pieces

Fixes #869
nit: "additional info" sounds like you're referring to something else.  Might be better as "this dictionary" or just "In the event of a compilation failure, values are copied ...".