Setting fork in run to be true and adding "-server" option to all runs.
Updated path for resources in cassovary-benchmarks Added an explicit exception if directory is not found.
core code for parallel random graph generation
graph generation benchmark
subset sampling benchmark
review fixes
Merge branch 'ParalellGraphGeneration' of https://github.com/szymonm/cassovary into ParalellGraphGeneration

Conflicts:
	cassovary-benchmarks/src/main/scala/com/twitter/cassovary/GraphGenerationBenchmark.scala
	cassovary-core/src/main/scala/com/twitter/cassovary/util/Sampling.scala