Bug 5349: (follow-up) tweak order transfer form

Bug 5349: (follow-up) tweak order transfer form

This patch implements some of the suggestions made
by Owen Leonard and brings the form closer in line
with other popup forms.  In particular:

- sets dimensions for the popup so that clicking on the
  link is more likely to open a new browser window, not
  a tab.
- ensures that the vendor search form is always visible
- adds a cancel link to make it more clear to library
  staff that they can abort the process.
- tweaks markup to better match the patron guarantor
  popup search form

Signed-off-by: Galen Charlton <gmc@esilibrary.com>