Added conditions to ensure the tutorial and portable projects are only available is the msbuild imports are present on the system.
Merge pull request #346 from 7sharp9/master

Switched the portable project to default to profile47 to match the current FSharp.Core
Merge pull request #345 from 7sharp9/bugzilla16725

Added conditions to ensure the tutorial and portable projects are only available if the msbuild imports are present on the system.