Portable Library (legacy) displays wrong target framework version.

[KevinRansom]

Opened on Codeplex by blainne

According to SO thread: http://stackoverflow.com/questions/24649958/portable-f-library-references-net-4-5-but-not-4-0/24657559#24657559

Portable Library (Legacy) project template states that it allows targeting 4.0 framework version. However, in project properties window of a project created with this template the "Target Framework" listBox allows only to select _".NET Portable Subset (.NET Framework 4.5, Silverlight 5, Windows 8)".

In fact, both the .vstemplate file and the .fsproj file created with this template have:

<TargetFrameworkVersion>v4.0</TargetFrameworkVersion> (the .fsproj file)

and

<RequiredFrameworkVersion>4.0</RequiredFrameworkVersion> (the .vstemplate)

[KevinRansom]

fixed #310