TPAC: Allow multiline buttons and other minor button work.

Allows using multiline buttons; instead of using opac-button
-class in the a-tag, wrap the a-tag in a div with
opac-multiline-button -class.

Changes the login help button so a longer button text
behaves properly and looks good.

Unifies the green OPAC button behaviour when hovering
a mouse over them; the input and button -tag buttons
did not change their color.

Signed-off-by: Pasi Kallinen <pasi.kallinen@pttk.fi>
Signed-off-by: Dan Scott <dan@coffeecode.net>

Conflicts:
	Open-ILS/src/templates/opac/css/style.css.tt2