assign random qid to a directory, and store this
minor: removed superfluous print statement
added lockfile to the requirements
quick & dirty hash module - warns if files have changed
mad sha1 updates sha1sums & qdsums
force qd hash update when creating new sha1
Major refactoring:
- storage is now modular, with two stores implemented:
  - sidecar (default: .*.mad)
  - mongodb (still preliminary)
- sha1sums are always created, automatically, and stored in ./SHA1SUMS
- experiments in storing provenance data (incomplete)