UI test code changes for new infra

1)Add upload_png_files to upload png files to web server
2)Taking care of process name changes
3) Fixed few minor script issues
4) Remove webui_tests_suite
Change-Id: I1f5e0ba3aed8ba8e132dee577dbbea979477d59f
Merge "UI test code changes for new infra" into R2.0