The default settings are wrongly show in the first boot

[Manuel de la Peña]

The upload and download limits initial show the values presents in the syndaemon default config file which are:

bandwidth_throttling]
on.default = False
on.parser = bool
on.action = store_true
on.help = Enable bandwidth throttling

read_limit.default = 2097152
read_limit.parser = throttling_limit
read_limit.metavar = DOWNLOAD_LIMIT
read_limit.help = Set the download limit (bytes/sec).

write_limit.default = 2097152
write_limit.parser = throttling_limit
write_limit.metavar = UPLOAD_LIMIT
write_limit.help = Set the upload limit (bytes/sec).

But because the default is no too have them enabled we should be showing the value to be -1 since otherwise it will confuse the user.

This bug affects the Qt UI.