Bot improvements

Hi Jiri, 

please accept my irc-bot changes

before bot recognized command in given messages:
```!help 
whatever ! nobody helps me
I am begging you for !help
```
now it only recognizes commands at the beginning of message
```!help
rhq-bot: !help
```
 2nd thing I did was a little bit security .. now only people from DEV set can use "echo" and talk through bot