Various fixes and tweaks to Valo

Various fixes and tweaks to Valo

- Added a new “quiet” style button, and an “icon-align-top” style, and
added an additional parameter for the borderless button style

- PopupView now has a proper animation-in and animation-out, with a
spinner showing the loading state

- Small fix to slider minimum size

- Fixed TextField text centering for IE8 and IE9

- Fixed Tree expand/collapse arrow clicking in IE10

- Tweaked Window shadow and modality curtain style

Change-Id: I48dab61c648363b8eb0c03dc3b3cbbc1289b94ed