This fix updates the style for buttons to better conform to the screen
by using weightSums.
It also makes layouts much more flexible across platforms by making
better use of the square aspect feature of LockPatternView.
Change-Id: I63677790bf0ac52707c8c356540ecd5dc50ca33b
Now, instead of having equal space overall above and below lock pattern widget,
the lock pattern widget is centered within the space above the button bar
at the bottom. Also, removing the line below the lock pattern widget per
romain's recommendation; it looks goofy with the button bar below.
see screen shots in http://b/2045023 for the differences.
