Only warn if symbol package can't be created because no relevant files
could be found. Closes #220
Floating feeds now honor stability settings
Closes #211

Conflicts:
	src/ripple/Nuget/FloatingFeed.cs
Fix rake create_gem which fails by copying files to file not a directory as expected.
Hacked the way ripple sets stabilities on nuget feeds to fit our needs
until https://github.com/DarthFubuMVC/ripple/issues/123 is implemented