Fixes issue #205

Modify the README to bring attention to building from source.
Modifications to allow building CommonAssemblyInfo.cs from the SLN
Change detection of Mono env to use the OS environment variable, Windows_NT value. This is in line with how NuGet does it.
Modify README to detail building from source.
Ensure build from MonoDevelop works.
Add note that git must be in your PATH
remove Version from VS build
tweaks to build instructions from source
shuffle targets around so git is only consulted for nuget release
target refactoring to only use git for nuget release
Auto-gen CommonAssemblyInfo.cs from VS, fixed hang issue. Release builds will consult git for versioning, Debug will just use 0.0.0.0
Merge pull request #206 from basho-labs/issues/lrb/205

Ready: Fixes issue #205