SLIDER-942: Slider agent fails with SSL validation errors with python 2.7.9.

SLIDER-1129: Completely remove dependency on commons-httpclient library from test code as well due to HADOOP-13382

SLIDER-1145: Work around hadoop 2.8 changes in DefaultResourceCalculator.normalize.

SLIDER-1150: Slider app fails to start on AmazonLinux.

SLIDER-1152: Resource leaks found in code.

SLIDER-1153: Code issues - 14 null pointer deferences found.

SLIDER-1154: Fix concurrent data access violations.

SLIDER-1156: OutstandingRequestTracker edits map while iterating over its entries.

SLIDER-1157: Code issues - integer handling issues.