only poll once with --interval 0
add multigraph support
ignore broken plugins that don't return a value at all
- some PEP8 cleaning
- try/catch exception for key_value
- socket error for carbon
- catch exception in multigraph also
- add catch for multiple exception in multigraph
- add exception catch to hello string read at least
added update_hostname

* gets the hostname from the the munin connection hello string
* does not override displayname if provided