[PM-1901] converting pegasus-analyzer tool to API (like status) and add test suite

[mayani]

• Code refactoring (in master) to make analyzer similar to the pegasus-status code that is called via the API, and thinning out of the CLI client.
• Get unit tests in for pegasus-analyzer

Reporter: @zaiyan-alam
Assignee: @zaiyan-alam
Watchers:
@zaiyan-alam
@vahi
Attachments:

[mayani]

Author: @zaiyan-alam

• Analyzer now contains a refactored api analyzer.py, which returns AnalyzerOutput object consisting of all info in serializable structured data classes
• The same common AnalyzerOutput structure is returned for either Files options or Database(default) option, no redundancy
• Thinning of cli tool, as it now it only prints the returned AnalyzerOutput structure from the api itself
• Single printing method in cli to render the returned AnalyzerOutput structure for either Files options or Database(default) option
• New features, bugs fixed : Files option now returns all info for failed jobs i.e more attributes, Tasks info, stdout/stderr etc. as compared to old tool (above pic)
• New --json option which returns the output in a serializable structure
• Testing : testing suite with almost 60 unit tests added, with coverage of almost 93%
• Updated docs regarding --json option & structure : https://github.com/pegasus-isi/pegasus/blob/master/doc/sphinx/manpages/pegasus-analyzer.rst
• All changes checked in with successful build and green tests on bamboo