Bug 18108: Sorting by author in opac summary

Bug 18108: Sorting by author in opac summary

To test:
1) Log into OPAC, go to your summary
2) Notice 'author' is in Title column, therefore unable to sort by
author
3) Apply patch and refresh page
4) Notice author has now been moved into Author column
5) Confirm sorting by author works as expected and sorting of all other
columns works as expected

Sponsored-by: Catalyst IT
Signed-off-by: Mark Tompsett <mtompset@hotmail.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>