except-regex option

Added option to exclude file paths that match the except-regex option from being ignored.  The usecase for this is when you want to ignore a group of files except for one case.  For example ignoring all exe files, except the .nuget/NuGet.exe file.

Also changed the behaviour when using init-branch, so that the you can specify these options there too.  Also if no regexes are specified, the default behaviour is to copy the ignore regex and except regex from the default TFS remote and copy it to the new TFS remote.