Update build tools, add ripple drawable & alter animation interpolators

I've made the following changes: 
+ Updated the build tools used for the sample and library grade files to v21.1.1,
+ Modified the animation interpolators from quadratic to cubic as well as changed the interpolation direction to represent the authentic motion part of the material design spec; where an object should enter/exit frame at peak velocity,
+ Added a touch feedback drawable to the action button that uses a ripple drawable for v21 and up,
+ Changed the action button font style/family to better match the material design spec,
+ Changed the action button font colour to be more neutral.

One or two small formatting changes were also made to some of the XML files to give them consistent formatting, too.