Completion of e2e tests including mocking apis

- settings.html updated with several build e2e replacements - adding the test app, angular mocks, http mock, visualization mock, and test app replacement script
- gulp file updated to add several e2e files to be inserted or used to replace via the htmlE2E factory function in "html:e2e" task
- Adding settings-app.js for use in e2e tests so that it can be used to replace the real app and thereby inject the spreadsheet-controls-http-mock
- Adding settings-app-replace.js to be used in the e2e build so it replaces the real app name with the test one
- Comprehensive e2e tests now in place which involve use of the mocks of apis and saving settings