Crash if number of blocks are less than number of cores/workers

https://github.com/wpgp/wpUtilities/blob/8d5dc9cb849a32c2eecf54a1d8943edeedeafb7e/R/wpSetAllValuesTo.R#L79

at L79 the cluster is initialized with x workers and at L98 you're populating the workers. if the number of jobs are less than the number of cores it crashes. 
