Fixed deadlock.

When you call timer.cancel(), it attemps to acquire a mutex which may
result in a deadlock.  By simply setting the active flag instead, we
achiev the same affect without the deadlock.
Bumped version.
[README] Updated versions, fixed broken link.
Bumped hadoop-core version to 1.2.1.
Merge pull request #8 from brndnmtthws/deadlock-fix

Fixed deadlock.