Don't put checkbox text on separate line (#475)

Don't put checkbox text on separate line (#475)

Manually render the "notify me" checkbox line in the account settings
to not put the form label as a heading but in the same line as the
checkbox.

Edit forms.py to use the label attribute for the caption.

Original patch modified by Sebastian Spaeth to 1) not translate the
checkbox label in the template, it is translated in forms.py already.
2) Simplify the HTML, manually constructing the <label> tag is not
necessary, WTforms does it automatically.

Author:    LotusEcho <Emma.C.Echo@gmail.com>
Modified-by: Sebastian Spaeth <Sebastian@SSpaeth.de>