Graphite integration

Linked to #168 and #184.

Graphite Integration in Thruk is now handled correctly : 
 * href is linked to Graphite UI and not only a png file. 
 * link in extra action for hosts and service are corrects (same href as previously)

All replacement of specials chars in hostname amd servicename are done in js, not perl. The html source code may help to debug if you encounter issue with that. 

Basically I created 2 templates , one for hosts and one for the services. I think the code is simple enough for everyone to understand it :)

Hope it won't break anything. I think not :yum: