Bug 19180: [FOLLOW-UP] Renaming all instances of 'name' variable to 'booksellername'

Bug 19180: [FOLLOW-UP] Renaming all instances of 'name' variable to 'booksellername'

... when referring to the name of the vendor.

To test:
1) Confirm vendor shows on webpage title (tab name)
2) Confirm vendor shows in breadcrumbs
3) Confirm vendor shows in heading when viewing basket ('Basket x (1) for
vendor')

Sponsored-by: Catalyst IT
Signed-off-by: Mark Tompsett <mtompset@hotmail.com>
Signed-off-by: Caroline Cyr La Rose <caroline.cyr-la-rose@inlibro.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
(cherry picked from commit 06b602b0976e2a8d53ff31f95a2213cbeb98e9cb)
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>