GUI-1044: UX Improvements for image picker in launch instance and launch config wizards

Implements the following for https://eucalyptus.atlassian.net/browse/GUI-1044

- Add border to image list table
- Constrain image list to display roughly four images at most
- Remove description and replace with search filter input label text
- Move image picker table above image id input field
- Add "Select" buttons inside image list for direct selection of images

Note that the following have *not* yet been implemented, pending further discussion…

- Border around filer set at left (tried it, but the interface looks much better w/o the border)
- Adding a "more" link for long descriptions.  @JMoLo : Suggesting we shelve this for a future improvement since 1) there's no way to detect if text takes up more than two lines and 2) long image names may cause additional wrapping