HTML structure for Settings header

- Title and Close button
- Usual 3 control buttons: Save, Cancel, Help
- Alert div container
(Settings) Adding header _bind and _cache code

- Added event handlers for control buttons (Save, Cancel, Help)
- Added elements to cache object
- Added empty _saveSettings private function
(Settings) Applying copy to header

- Added copy to english locale JSON
- Hiding alert container
- Initializing and showing i18next copy data
(Settings) Making header buttons sticky

- Applying stickyness to header control buttons (Save, Cancel, Help)
- Correcting header title to be an <h2> and not <h1>