Add back button template

New button that
tighten up ui

Pixel peeping against native iOS 7. This should be within +-1 device
pixel.
re-adjust the margins so that it's always centered

Keeping the text centered when it's not overflowing is difficult while
keeping
it compat. with older androids. This will manually adjust the margins
so that
different button widths can be used and still maintain center.
add a global listener for back button

calls history.back to go to the previous iron router route. This should
prob.
check to see if the history.back will take you out of app and into
another
domain (non phonegap apps).
listen for click inside page template, update edit message