Changes filter form heading to "Show Only", and simultaneously specifies submit button to read "Submit". Closes #67 and #71

Signed-off-by: Matt Bernhardt <mjbernha@mit.edu>
Moving the database connection later in the site heading, allowing branding to appear in an error state;
Implementing a somewhat nicer error message on database failure.
This is related to #54

Signed-off-by: Matt Bernhardt <mjbernha@mit.edu>
Increasing font size (14px) and line height (18px) to match MIT Libraries styles. This closes #40

Signed-off-by: Matt Bernhardt <mjbernha@mit.edu>