Capture and transmit HTML content

[kylepolich]

• Introduce some notion of "types" to your messages sent to SNS.

For messages from #10, type type is nav

For messages from this Ticket, the type is raw.

• When a page has fully loaded for the first time, capture the raw HTML (same as you would see if doing View > Source)

• Add some maximum size limit. If the page content is too big, only transmit the first N bytes