Add Content files to the solution explorer

[bisen2]

Currently, the F# Solution Explorer only shows source code files (those within a <Compile Include="..." /> element). However, the compiler also allows the <Content Include="..." /> to publish files with the compiled project. I think it would be a good idea if Ionide could recognize these files and display them in the solution explorer, perhaps in their own folder like 'Package References' and 'Project References'.

If this is a change you would be open to, I would be happy to help out with implementation.