Merging Pull Requests from @htgoebel #566 #567

Hi,

It's basically a merge of the PR made by @htgoebel a LONG time ago. I try to keep the same bahavior as before : 
* Nag format for some log in ALL handler (console, file, brok)
* Human timestamp only in console / file
* Only one human timestamp format (previously 2)
* Brok only for level INFO and higher
* Set level sets actually level on console / file (not on brok handler)
* Color are still supported in console, mapping for color level is hard-coded

What we can improve now : 
* Separate monitoring log (such as the one print by naglog_result) from Shinken logs. Shinken is an application, it have to provide its own logs and loggers.
* Use parameter for TimeRotatedFile instead of hard-coded 5 (file limit)

Feel free to commen it, I may have forgot some corner stuff. quick_test.sh is OK on my side so I think it's pretty fine ;)

Edit : Well I could add some comment in the code / doc at least :)