Don't call apache.start() in service.unpause()

service.unpause() calls render_configs() which calls apache.render_configs(). Within that, it will call apache.start() so it is not needed here. It also handles config changes requiring graceful reload better.

Reviewed-on: https://code.launchpad.net/~hloeung/ubuntu-repository-cache/only-reload-apache2-when-needed-4/+merge/398419
Reviewed-by: Paul Collins <paul.collins@canonical.com>