Make contributor name field larger, add placeholder to date field

I noticed many contributor names (particularly couples) were
considerably too long to fit in the field in the inline form as it was
previously sized. So I increased it to a 3-width column instead 2-width,
and decreased the size of the Add button to make room.

There was also some confusion on the date format exepected or allowed,
so I added a placeholder of mm/dd/yyyy. The /yyyy part is optional, but
I can let the users know about that.
Trim the name entered AND the name stored in the database on compare

There was a case where a contributor name was stored in the database
with a trailing space, and the code to check to see if the name entered
was a known contributor failed to detect it because it was trimming the
input, but not the name in the Giving.contributors list retreived from
the database. Now it trims and downcases both before comparing.