Web::HTTP#_request: allow Rex opt level overrides

Allow overriding options at the Rex level when performing requests
via the Auxiliary::Web::HTTP wrapper.

lib/msf/core/auxiliary/web/http.rb

@@ -271,6 +271,8 @@ class Auxiliary::Web::HTTP
 		method  = opts[:method].to_s.upcase || 'GET'
 		url	    = url.is_a?( URI ) ? url : URI( url.to_s )
 
+		rex_overrides = opts.delete( :rex ) || {}
+
 		param_opts = {}
 
 		if !(vars_get = Auxiliary::Web::Form.query_to_params( url.query )).empty?
@@ -288,7 +290,8 @@ class Auxiliary::Web::HTTP
 			'uri'     => url.path || '/',
 			'method'  => method,
 			'headers' => headers.merge( opts[:headers] || {} )
-		)
+		# Allow for direct rex overrides
+		).merge( rex_overrides )
 
 		opts['data'] = body if body