added second constructor to allow hadoop JobConf configuration. See #58.
Update to latest versions of Cascading (2.2.1) & Tika (1.5)
Merge with GitHub
Merge branch 'master' of github.com:rockwalrus/bixo into rockwalrus-master
Merge in pull request
Only call TupleEntryCollectors when Cascading allows it.

Cascading expects the TupleEntryCollectors to only be called when a
thread is currently in a method such as operate or cleanup.  This patch
adds a semaphore to prevent other threads from calling a collector if
one of the appropriate methods is not being executed.  Not doing this
resulted in ConcurrentModificationExceptions and other spurious
problems.