Some sites don't allow you to login without clicking on a button to open a retracted modal.
This update to the login code allows Brozzler to click on all elements that we think are related to opening a login modal.
Then, if there isn't a regular form, we will attempt to fill out abnormal form schemes.
The test_try_login test has been expanded for the new type of login form we are supporting.
Add unit tests for the code that detects and tries to use login forms
automatically (`Browser.try_login`).
Add `htdocs/favicon.ico` because it is loaded automatically when the
browser tries to use the test web server and it causes a "missing"
warning.
Create a new dir `tests/htdocs/site11` which is used for login related
test html files.
