Convert all forms to submit on enter

[emcniece]

Currently there is a mixture of keypress detection and form submission handling. These should be unified: instead of watching for keypresses, each form should handle a submit event and cancel the default action.

This issue might be useful. Some forms have specific functions (#login for example) that need to be called on submission. If the function name is stored in a data-action="do_login" format, we can avoid a switch in the form submission handler and stick with a global form submission statement.