Bug 10157 - koha-email-enable error handling

Bug 10157 - koha-email-enable error handling

koha-email-enable now
- Checks the instance exists.
- Checks if email is already enabled.

Regards
To+

Sponsored-by: Universidad Nacional de Córdoba
Signed-off-by: Robin Sheat <robin@catalyst.net.nz>
Signed-off-by: Jared Camins-Esakov <jcamins@cpbibliography.com>
(cherry picked from commit 1126dd8bf3e3f386acfc007bc6e3310cc5320100)

Signed-off-by: Jared Camins-Esakov <jcamins@cpbibliography.com>
(cherry picked from commit 0526bc3fa72ed6f5e7c13d581a051bd6894374f2)

Signed-off-by: Bernardo Gonzalez Kriegel <bgkriegel@gmail.com>
(cherry picked from commit 0526bc3fa72ed6f5e7c13d581a051bd6894374f2)