It turns page.size() and page.setSize() methods are slightly
confusing since there multiple different sizes (layout size,
content size, viewport size..)
This patch renames Page.{size,setSize} methods into
Page.{viewportSize,setViewportSize} methods to avoid confusion.
Certain examples rely extensively on the originating PhantomJS
examples.
This patch fixes license headers of these examples to mention
PhantomJS authors.
