Bug 9587 Follow up to fix the problem Katrin identified

Bug 9587 Follow up to fix the problem Katrin identified

Signed-off-by: Bernardo Gonzalez Kriegel <bgkriegel@gmail.com>
Comment: Solve that problem, but now koha-qa complains about tabs
in C4/Context.pm.

Signed-off-by: Katrin Fischer <Katrin.Fischer.83@web.de>
Tests done:
1) System preference 'Persona' added correctly.
2) Persona off, normal login still possible
3) Persona on, Persona login works
4) Persona logout works
5) normal login still possible
6) normal logout still possible

Persona is off by default and uses the primary email address
from the patron account.
Signed-off-by: Jared Camins-Esakov <jcamins@cpbibliography.com>