honor new --exitCode when more than one descriptor
Merge pull request #34 from drewfish/exit-code

honor new --exitCode when more than one descriptor
Retry , screenshot and html source storage for failed testcases  , deleting old report files, xml-writer implementation
fixing unit tests
fixing group param
Supporting comma separated descriptors
--color, --keepIstanbulCoverageJson options added to commandline, fixed report summary bug
using ycb module now, and  support for base descriptor file.
removing unwanted console.log
reducing loglevel for few debug statements.
jslint fixes
adding support for common js lib
v0.0.72 release