small fixes to cli program and example.js

[diffalot]

this might fix #11 and #6

• use an app name when creating client
• throw error messages when argv length is incorrect
• use server.on('publish', ...) instead of broadcast
• use argv.host and argv.port in bin when broadcasting and subscribing

[mafintosh]

:+1:

[mafintosh]

Thanks. Out in 4.3.1

[mafintosh]

Also really cool username!