Reverse proxy - setHeaders & hideHeaders

This adds the possibility to set/hide headers on a reverse proxy config, eg:
````javascript
	locations: [
		{ 
			name: 'root',
			regex: /.*/,
			setHeaders: {Host: 'www.cahri.com'},
			hideHeaders: ['Set-Cookie'],
			pipeline: [
				['proxyPass', "nodeOne"],
			]
		}
	],
````