Update several docker-library images

- `golang`: removed most of the tags now (only the latest patch release of each of the two major versions now; 1.2 and 1.3)
- `php`: update and add a ton of tags that were missing (`php:cli` to match `php:apache`, `php:5.6`, etc.)
- `python`: update several versions, especially to make sure 3.3 has pip
- `redis`: chown of volume data and redis-sentinel symlink