Add support for DOWNLOAD_URI option.
* Fixes some comments that were no longer accurate.

Conflicts:
	modules/auxiliary/gather/apple_safari_webarchive_uxss.rb
Rename DOWNLOAD_URI -> DOWNLOAD_PATH.

Conflicts:
	modules/auxiliary/gather/apple_safari_webarchive_uxss.rb
Update print_status labels.
Land #1777, usability fix for Safari module
Fix a logic error in HttpServer

When a module is configured to listen on the INADDR_ANY interface, with
a payload that does not have an LHOST option, it attempts to determine
the srvhost from a client socket which would only be available when the
module has included the TcpClient mixin (i.e., it is both passive and
aggressive stance), causing a NameError for the undefined +sock+.

This commit fixes the problem in two ways:

1. It changes the default cli in get_uri to be the module's self.cli,
   which should always be set when passive modules would need it (e.g., in
   the on_request_uri method).

2. It adds a check to make sure that the calling module has a sock
   before trying to get its peerhost. This was @marthieubean's suggested
   solution in #1775.

[Closes #1775]
Add a reference for Safari module
Trivial description cleanup