Prefers tasks with more dependents in scheduling
Merge pull request #462 from Houzz/schedule_for_dependents

Prefers tasks with more dependents in scheduling
add support for spark 1.x
fix for python 2.6
include priority and resource information in visualizer
Fix deprecation warning when importing luigi.hdfs.

You will still see a deprecation warning when creating an
HdfsTarget if you haven't specified a config.
Merge pull request #485 from jcrobak/fix-luigi-hdfs-deprecation-warning

Fix deprecation warning when importing luigi.hdfs.
Merge pull request #483 from RUNDSP/spark-1x-job-pr

add support for spark 1.x
Merge pull request #484 from Houzz/viz

include priority and resource information in visualizer
Adds DISABLED status for tasks in scheduler.

Tasks can get the disabled status either through scheduling or from repeated
failures. The scheduler handles disabling via repeated failures, and tasks
disabled this way are automatically re-enabled after a fixed amount of time
or when pruned. This allows tasks that are repeatedly running and blocking
progress on other tasks to be pushed aside until someone can have a look.

Tasks can be set as disabled via the disabled parameter in Task. Tasks with
this parameter set to true have will be scheduled as disabled and will not be
run. This disable can only be removed by setting disabled to false in the task
and re-scheduling it. This makes it easier to stop running broken tasks without
having to manually figure out all upstream dependents and remove those as well.