Fix #68: Add build of FSharp.Data.TypeProivders.dll to open source edition

This adds the build of FSharp.Data.TypeProviders on Linux/Mac, see
https://github.com/fsharp/fsharp/issues/68
Merge pull request #108 from funnelweb/issue68

Fix #68: Add build of FSharp.Data.TypeProivders.dll to open source edition
Merge pull request #109 from funnelweb/fix107

Fix #107 - Installing on Mono 3.0.4
Merge pull request #110 from funnelweb/fix107

Document how to make 'debug' and 'release' builds on Mac and Windows respectively
Update README.md