Adds unit tests for db_task_history, bug fixes

Uses sqlite3 in memory mode for db.
If sqlalchemy can't be imported, skips the test rather than failing.
Adding a manifest file for distutils so that bin/luigid is included in the source tarball that gets built
Hadoop binary path can now be specified in config.  Sets are converted to tuples in Task class.
Additional unit tests in the hdfs module and a new hive client command class supporting the Apache release of Hive, which returns a non-zero exit status if tables and partitions dont exist
Merge pull request #151 from JoeEnnever/db_fix

Adds unit tests for db_task_history, bug fixes
added File.copy

Use case: when a file, e.g. from an ExternalTask lives
on a read-only filesystem, you cannot `move` it.

One unittest included.
Merge pull request #158 from miku/feature/filecopy

added File.copy
Fixes visualizer for taskids with _ and numbers in the name
Add Scalding support

Change-Id: I5c3ef04d7cc2db8cfb5944875bbeecb95b5d86e0
Merge pull request #110 from spotify/neville/scalding

Add Scalding support
only fail if given an egg file, not a directory ending in .egg
Fixes templates, reverse_url doesn't work
Merge pull request #162 from JoeEnnever/templatefix

Fixes templates, reverse_url doesn't work
Allow configuration of smtp for notifications.

Defaults are all the same as before, but you can now
specify ssl, login, server host, etc.
Removing upstream_status from serialization info
Moving upstream code to do iterative graph traversal
Adding gzip support to application calls
Merge pull request #163 from jcrobak/config-email

Allow configuration of smtp for notifications.
bumped the version number and uploaded to pypi
Merge pull request #152 from gf-atebbe/cmmaster

Apache HiveCommandClient
Static files should work now in PyPi.

Bumped version number even more.
Improved the formatting
Check it out: https://pypi.python.org/pypi/luigi
Removed a spurious traceback from the PyPi installation by bundling README.md