Improve the behavior of local excludes

[DavideRossi]

Maybe just apply to the remote fileset the same filtering that is used to the local one? That would mean use the local .upback.exclude to filter remote elements... If you have suggestions just add comments below.

[mn89h]

I guess that would make sense. Until now I haven't come across the need of filtering as I am using seperate folders. I think it's a nice to have for those who want to retatain their folder structure in the web storage while not fetching unneeded files, especially when there are multiple clients.