Added nuspec packages for Fsharp.Core for both Mono and Microsoft signed versions.
Renamed package names, corrected owner and version numbers.
Merge pull request #318 from 7sharp9/FsharpCoreNuget

Added nuspec packages for Fsharp.Core for both Mono and Microsoft signed versions.
Unicode letters & operators

examples:
let ★ x = x + 5
let (|★) x y = x + y
let summ = ★ 5 |★ 5
comment about \So infix operators