Updating to release NuGet.config
Updating to dev NuGet.config
Adding ability to monitor file changes for PhysicalFileSystem

1. This includes the implementation & tests.
2. A modified IFileInfo interface (This will require changes to MVC repo - A PR will be sent out after this changes are approved.).
3. File system watcher turns off when there are no files to monitor and turns on when files are to be monitored.
4. Need to add a test to verify that file system watcher turns off if no files to monitor.
PR feedback

Addressing some PR feedback + offline discussion comments from Chris.

Also added a test for the NoopTrigger.
More PR feedback
Adding a IFileSystem level Watch method

Currently IFileInfo has the CreateReadStream overload which gives ability to monitor a file change. But this does not allow monitor file create events.
With this change it allows monitoring file/directory create changes. As well it supports regex based filters to monitor files - the patterns are same as what is supported in project.json for fields like "code", "exclude" etc.