Wrk Summarizer Parser Integration

+ Added DescriptorImpl extension to WrkSummarizerParser
+ Added DataBoundConstructor annotation to WrkSummarizerParser
+ Made cosntructor for WrkSummarizerParser public

+ Cleaned up HTML in report parser help file
+ Added default value for wrk to report parser help file
+ Added note to report parser help file about wrk output report

+ Added wrk to index.jelly's list of supported output formats/plugin
  description