Update qs dependency

See https://nodesecurity.io/advisories/qs_dos_extended_event_loop_blocking
Merge pull request #54 from pdehaan/patch-1

Update qs dependency
version bump
Added inMemory option to keep data in a Buffer and not automatically write to disk
Added inmemory documentation and package version bump
Tweaked inmemory documentation
Merge pull request #62 from jpfluger/inmemory

options.inMemory added (is backwards compatible)