Allow navigating between pages in Page Editor by swiping and show adjacent page edges.

This issue has been migrated from mozilla/webmaker-android#1823.

It was originally written by flukeout on Mon May 11 2015 and had the following description:

Page editor should show the adjacent page edges, including diagonal neighbors too and allow swiping to navigate to other pages.

On Mon May 11 2015, thisandagain commented:

This is a fairly large technical lift. Adding to backlog for now but something we should address in 1.0.1 IMO.

On Tue May 12 2015, flukeout commented:

**@**thisandagain For now, let's just remove the edges from this view altogether. Filed in mozilla/webmaker-android#1824

On Fri May 15 2015, Pomax commented:

this totally got teh dones