Accept "on" value for remember me checkbox input value

Tested by adding a remember checkbox into the project default template login. I verified that a "remember_token" gets saved to a non-null value in the users.json after login.

I've copy&pasted my patch for adding "remember me" functionality into the comments of this pull request.

```
Accept a value of "on" for login screen's "remember me" input value.
This is what gets sent as default by the browser when an
<input type="checkbox"> is checked.

Previously only "1" was accepted which meant checkboxes would need to
explicitly specify a value="1" in their definition.

Fixes #96
```