Low: apache: Allow basic server request monitoring without requiring server-status to be enabled

By default, the apache agent attempts to detect the location
of the server-status url and retrieve the contents of that URL.
If no regex is set, all this agent does is verify some sort
of html file exists at the server-status url.  Essentially in
the default use-case, the agent is just verifying that the agent
can successfully request something from the webserver.

Requiring the user to enable the server-status feature
just to verify a request/response from the server shouldn't be
necessary.  This patch allows the agent to fall back to
doing a basic http header request of the website's index
if the server-status check fails during a monitor... This will
only occur in the very basic use-case where a user has
not defined any statusurls, regex patterns, or custom test cases.