Fix bug in cookie pasing. Actually, page parameter incorrectly defined.
Don't use instance variable for cookie in Page::Request.
Move get_nav method from Page::Content to Page::Request.

Better to use the page nav directly from Page::Request. Seems cleaner this way.
No need to use an instance variable for main_doc.
Save initial Page::Content object directly.
Pass HTML doc to Page::Content. Add check for :meta so test passes.
Remove get_nav test for Page::Content.
Add starting point for RSpec usage.