Created pre-defined test subsets

Created the following pre-defined test subsets which can be invoked
by passing QUICK1, QUICK2, PART1, or PART2 to the --tests input
parameter :
  QUICK1 - Current tests used by the phoenix_quick job. Takes
           approx. 15 minutes to run.
  QUICK2 - Tests selected based on whether it had failed before
           on elapsed time. Takes approx. 15 minutes to run.
  PART1  - First half of the phoenix test divided by time. Takes
           approx. 30 minutes to run.
  PART2  - Second half of the phoenix test divided by time. Takes
           approx. 30 minutes to run.

Also fixed file to conform to Python's PEP8 Style Guide.

Change-Id: I13f452511d821695b2f52b41a749237d4fc628da