New release

Fixes

• Return empty dict instead of None from all API methods (by @scop)

Enhancements

• Add more network config, syslog, and voice methods (by @scop)
• Auto-append trailing slash if URL doesn't end with one (by @scop)
• Remove @authorized_call (This was no longer a good idea, because authorization requirement differs by modem type and firmware version) (by @scop)