addresses issue 216

Successfully tested against a locally installed MongoDB 2.6.5. Please
test and review.

Don't merge / release before all known MongoDB servers are updated to
a version >= 2.4
Merge branch 'fix/issue216' of github.com:radical-cybertools/radical.pilot into fix/issue216
Copy from Andre's version on a branch.
revert example changes
attempt to cancel pilots timely...
snapshot
Module fix for local python package conflict.

(Also removed gsissh as I dont think that exists for archer)
resolve conflicts from merge from devel
Merge branch 'devel' of github.com:radical-cybertools/radical.pilot into devel
make instructions clearer on data staging examples
resolve conflicts from merge with feature/unit_restart
remove debug print
typo
remove debug dumps
add debug logs to trace cancellation of pilots
fix logi error on state check for pilot cancellation
take care of cancelling of active pilots
be more resilient on pilot shutdown
Remove workaround after prompt and adequate response by Archer staff.
small changes to example and debug logs