allow to set onelab numbers and strings from command line

Hi Christophe,

I added the possibility to assign a ONELAB number/string using its ONELAB name via the command line.

This can be rather handy when you drive a binary ONELAB client on a machine without a GUI for instance.

I named those options -setolnumber/-setolstring as an echo of -setnumber/-setstring.

Do you think it makes sense to merge that in the master version? Or you perhaps have another idea/approach in mind?

Have a nice weekend! Nicolas.