DRILL-3749: Upgrade Hadoop to 2.7.1
Upgrades Hadoop dependency from 2.4.1 to 2.7.1. This allows us to take
advantage of the latest S3 filesystem support. Includes update to Hadoop
methods and updated curator library (2.7.1)
Also includes adding @Ignore to TestDrillbitResilience.cancelAfterEverythingIsCompleted() as it appears to be subject to a timing error.
See: DRILL-3967
This closes #203
