default value if dhparam isn't defined in the pillar.

Improvement - Disable reload of nginx when enabled=False (previously the nginx was always reloaded if settings.config != None; even with enabled=False)

In order to improve security and ease of use, added creation/generation
of dhparam file.

Removed comment after testing that this change works with xenial

Fixes #70

Build NGINX from source with nginx.ng state with support for passing
compile time flags necessary for installing modules such as more headers
by the openresty project.

On Ubuntu, you can take advantage of Personal Package Archives on Launchpad simply by specifying the user and archive name.  On other apt-based systems this must be the complete entry as it would be seen in the sources.list file.