Configurable delay after authentication, support for Nickserv authentication, some language fixes

Per need to use the bot in freenode,
1) added support for authenticating to atheme/NickServ services
2) to enable joining after authentication is complete, added a configurable delay (config.yml setting "authdelay: X" - which defaults to zero if no number is given - in seconds) and in that process separated the channel joins to a separate function which the authentication calls
3) fixed some mostly minor language issues, as "signed on" doesn't explicitly mean connecting without authentication