Added F# library and sample projects
Added F# specific actor helpers
F# updates

Updated build fake script to build Stacks.FSharp
Added assembly info to Stacks.FSharp
Enhanced executor api a bit
Bug fix: Busy wait executor fixed Post()

Busy wait executor correctly posts work as synchronization context on a queue instead of executing them on threadpool
Added doc comments to F# version.
Updated 3rd sample for F#.
Merge branch 'FSharp' into develop