Added support for Redis 2.8 and changed default to 2.8.3

- Removed bundled redis distribution.
- Updated the templates to avoid deprecation warnings.
Support including custom conf files when defining instances
Specify versions in Modulefile
Allow parameters to be defined for the default redis instance
Pass all the parameters to the default instance
Properly include the redis_include_conf_path in the template
Expose more redis configurations when defining an instance