Merge pull request #17 from sergey-tihon/master

Site for facio was added by @sergey-tihon.
Modified .fsproj files so they work correctly when VS2013 MSBuild tools are installed on a system with VS2012 (but not VS2013).
Re-install NLog package when retargeting facio projects to different framework versions.
Fixed an inaccurate logging message, and removed an unnecessary comment.
Removed the Facio.Support.LegacyInterpreters project -- we now use the FsLexYacc.Runtime package instead.
Removed the FSharp.Core reference from the Facio.BuildTasks project. We're not using any functionality from FSharp.Core in there anyway, and it allows us to implement a solution for the assembly-resolution issue which arises at build-time on some systems.
Implemented an assembly resolver helper which gets installed whenever one of the build task classes are created; this fixes the crash on some systems were FSharp.Core 4.0.0.0 wasn't found (it's needed by ExtCore) because binding redirects aren't applied by MSBuild.
Fixed multiple imports of NuGet targets file in some projects.
Modified the way the error message is presented if the NuGet targets file isn't found when building the projects, so it works correctly on Mono.
Updated release notes for 0.8.7.