Content Pack treatment of entites with unique name

## Expected Behavior
When installing an entity with a unique name constraint the installation process should
allow me to enter a different name for the entity, when the configuration of the found entity
differs from the to-be-installed.

## Current Behavior
When finding a entity with the same name on the system, the install process will treat it as the
same entity (even if the configuration does not match).

## Possible Solution
- Check for configuration when comparing two entities.
- Ask for a new name when installing.

## Your Environment
* Graylog Version: 3.0 Rc1 (dcb2755b21241372f267f512d2057d5dfa7763e5)