sub_organizations_plugin: Add page that shows all sub_organizations of
given organization.

(ActionItem 2499)

Signed-off-by: Daniel Bucher <daniel.bucher88@gmail.com>
Signed-off-by: Arthur Del Esposte <athurmde@yahoo.com.br>
sub_organizations_plugin: Add sub organizations block.

(ActionItem2499)

Signed-off-by: Daniel Bucher <daniel.bucher88@gmail.com>
Signed-off-by: Gabriela Navarro <navarro1703@gmail.com>