Fixed SGF uploading issue
Fixed SGF uploading issue

Not all platforms have mime types setup for sgfs (duh), so now we just
filter based on filename instead of mime type.

Fixes #39

DmitriyKirakosyan/online-go.com,lemurek/online-go.com,DmitriyKirakosyan/online-go.com,DmitriyKirakosyan/online-go.com,BarneyStratford/online-go.com,BarneyStratford/online-go.com,online-go/online-go.com,online-go/online-go.com,lemurek/online-go.com,lemurek/online-go.com,BarneyStratford/online-go.com,online-go/online-go.com,online-go/online-go.com,lemurek/online-go.com,BarneyStratford/online-go.com,DmitriyKirakosyan/online-go.com,online-go/online-go.com