i. Changed access specifier on casemodule.Case.addImage() to public, so other modules can access it
   to display a newly added image in the UI.
ii. Fixed the names of icons in HTML report to go with the recent renaming of some Web artifacts.
Make HTML report more robust with artifact names in the HTML and icon files.
Merge pull request #252 from raman-bt/master

i. Changed access specifier on casemodule.Case.addImage() to public, so ...