Added conditions to ensure the tutorial and portable projects are only available is the msbuild imports are present on the system.
Switched portable project to default to profile47
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.