Several improvements

Sorry for single huge pull request, but I did many improvements for my project in separate repository, now decided to split them to small commits here and offer to pullrequest.
My improvements:
 - improved search bar so that it looks more like search bar (added bootstrap 3 magnifier icon)
 - fixed issue with CheckboxList used as inline editing control (cbl::getControl() returns string instead of Html, resulting into crash with additional class=>form-control)
- customizable class of row action button (for nice colored buttons with no need to write a template)
- added onPrepareTemplate(ITemplate) event to i.e. bind custom latte filters
- added possibility to add new records via the grid, just like inline editing of new record