makeConfig: Specify all settings and save to config object
In sorhawell/fastRditijuu: Easy cluster computing

Specify all settings and save to config object

1	makeConfig(...)

`user`	username
`host`	server (will connect to user@server)
`keyPath`	specifiy file and path for private key, if NULL non or system default.
`packages`	char vector of package names (can be empty)
`Rscript`	execute by Rscript or R CMD BATCH (former only supported on gbar, ladder no verbose)
`async`	return after starting job? returned value is ticked to fetch result when job completed
`qsub.walltime`	only relevant for async=T or lply, job time limit on Torque('qsub')-cluster
`qsub.proc`	how many processes to ask for per job, 1 unless using doParallel etc.
`qsub.nodes`	how many nodes to ask for per job, leave unchanged if in doubt