Layout Sharing/Embedding

[dasgarner]

Allow a layout to be shared using a link and optionally embedded:

• Setting to enable/disable URL sharing
• Setting to turn embedding on/off which effects the framing headers output
• A separate entry point for previews which uses PSK based authentication
• Resources served from the CDN if one has been configured (links to be unchanging so they can be cached by proxies, etc)
• Meter the bandwidth consumed (useful for service providers)
• Include basic proof of play analytics which tie an IP address to a play of the layout
• A dashboard for users which shows all embeddable Layouts currently shared with them and allows them to preview each one