Update e2e tests to use mock files now from widget-tester module

- Updating e2e test HTML to point to widget tester mock files for gapi-picker and http-mock
- e2e test HTML ensures name of http-mock module is the new one used from widget-tester
- Changed mock window function name to newly named pickFiles from widget-tester
Merge pull request #37 from stulees/chore/update-e2e-mocks

Update e2e tests to use mock files now from widget-tester module