add option to reset permissions assigned to a user

issue #175
people keep breaking the test sources

please use your IDE to refactor :P
prevent resetting permissions without having the userpermissions:edit permission for that user
properly reset stream permissions when saving (for removing permissions)

issue Graylog2/graylog2-web-interface#175
pick a default time zone for new users
field value alert type Graylog2/graylog2-server#356
add a default group (reader/admin) to ldap settings

to allow ldap users be readers by default this lets you assign a permission group to each newly created user.
changing the default group later will not affect the newly created users (unless you can tell me a good algorithm on what permissions to keep)

issue Graylog2/graylog2-web-interface#437
Merge git://github.com/Graylog2/graylog2-web-interface into develop