Uses mkdir function in HdfsAtomicWritePipe init
Fallback since older versions of Tornado can't handle max_hader_size
use amazon ses for emailing
Adding ordereddict dependency to debian/control
Merge pull request #417 from freider/ordereddict

Adding ordereddict dependency to debian/control
Merge pull request #413 from spotify/erikbern/max-header-size-fallback

Fallback since older versions of Tornado can't handle max_hader_size
Switch to using POST for RPC requests.
Fallback to GET if scheduler doesn't support POST.
Remove GET request size workaround.
set permissions of pidfiles to 777

This commit also features some super minor refactoring of luigi.lock
Merge pull request #411 from campanja/http-post-in-rpc

Switch to using POST for RPC requests.
Remove deprecated code from hive.py
Merge pull request #421 from spotify/erikbern/pidfile-777

set permissions of pidfiles to 777
seperated notify commands for ses and email
Merge pull request #422 from spotify/arash/remove-deprecated-stuff

Remove deprecated code from hive.py
renamed notify to send_email, removed globals()
Refactored luigi.worker a bit to use multiprocessing

...instead of os.fork and os.wait

This commit features the following stuff
- multiprocessing instead of os.fork
- Added a bunch of unit tests to run with multiple workers
- Fixed MockFile to support multiple processes
- Multiple processes are now supported even with a local scheduler

Other things I had to fix that was marginally related:
- Added --no-lock to a bunch of tests
- Fixed an issue in lock_test.py that triggered an error on my machine

I have no idea if/how this will work on non-Unix platforms (eg. Windows). On thing that should work (in theory) is to replace multiprocessing.Process with threading.Thread. I doubt that the previous code was working since it was relying directly on os.fork.
Merge pull request #407 from Houzz/simplify_atomic_mkdir

Uses mkdir function in HdfsAtomicWritePipe init
Merge pull request #419 from spotify/erikbern/worker-multiprocessing

Refactored luigi.worker a bit to use multiprocessing
Merge pull request #416 from tresata/notifications-boto

Allow use of Amazon SES for notification Emailing