LP#1706415: Address usability issues with bottom-of-page menus

LP#1706415: Address usability issues with bottom-of-page menus

Dropdown menus that appear at the bottom of the page in the web client had some
usability issues because their contents fell below the screen. This commit
adds a little space at the bottom of all web client pages and also makes
three bottom-of-the-page menus "drop up" instead of down. The three menus
are the stat-cat menus that appear at the bottom of the user registration
form, the Z39.50 actions menu, and the create reports template actions menu.

Signed-off-by: Kathy Lussier <klussier@masslnc.org>