Use jemalloc as the main memory allocator

The research showed that CS behaves inefficient using default(LeDough) memory allocator. MA either doesn't release the mmap-ed memory allocations or reuse them. This produces "leak". The only workaround for this is to restart CS.
jemalloc is the solution of choice b/c CS displays a way more behavior when used with jemalloc: it releases mmap-ed memory or tries to reuse it thus decreases resident memory usage.