Added  command line options for all GUI elements

/nosave - Prevents SHARE from saving the settings to the registry when
exiting.
/username <username> - Username used to authenticate onto the SHARE
server
/password <password> - Password used to authenticate onto the SHARE
server
/plexserver <url> - URL where the Plex server can be accessed
/syncserver <url> - URL where the SHARE server can be accessed
/downloadfolder <path> - Path to save any requested items
/autostart - Starts the SHARE client minimised and automatically syncs
every 12 hours
/skipsectionids <comma separated list> - A comma separated list of Plex
sections which should not be synced to this server