Bug 22029: Google plus has been removed from the social links.

Bug 22029: Google plus has been removed from the social links.

For testing:
1) Make sure SocailNetworks is enabled
2) Find a book and verify that in the social links, there is a Google
Plus option
3) apply patch and verify that the Google Plus option is no longer there

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
(cherry picked from commit 380e57ed72aa3b11e91b3897501b9966392a3eaf)
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>