another fedora18 slave for jenkins

[Eyal Edri]

we're running out of space on current f18 slave (only has 20gb disk),
and since we're moving most of ovirt efforts from f17 to f18 i suggest 
upgrading one of the f17 slaves [1] to f18. 

we'll still have jenkins.ekohl.nl running fedora 17.

this will help us running more jobs on f18 and avoid out of space issue,
at least for the short run.

any objections? 

[1] fedora17-slave-vm01.


Eyal.