Mono support

*revert .fsproj files from VS2013 to VS2012 while xBuild isn't fixed
*update to latest NuGet which solves the trailing space problem and doesn't require the consent envvar to be set
*disable silverlight and portable versions on mono
*add mono compiler path for documentation tests
*fix build.fsx and build.sh
Update WorldBank tests
Merge pull request #211 from ovatsus/master

Mono support
Fix compatibility with F# 3.1 for portable version
Merge pull request #213 from ovatsus/master

Fix compatibility with F# 3.1 for portable version
Fixing some typos in te Freebase sample
Automatically restore packages during the build
Fixing some typos in the CSV sample
Fixing some typos in the Http sample
Fixing some typos in the JsonValue sample
Fixing some typos in the JsonProvider sample
Fixing some typos in the XmlProvider sample
Fixing some typos in the WorldBank sample