GitLab

 - Adds the circular throbbing touch point view that the user interacts
   with during touch calibration.
 - Adds the hint box view that contains the hint message as given in the
   UX specs.
   (https://drive.google.com/file/d/0B_2Uyb2Rhx2OU0FIbXUyMkhMZlE/view)
 - Adds required resource strings for hint box messages.

Working protottpe(The video is the entire prototype. This change only
involves adding the touch point and hint box.):
https://drive.google.com/a/google.com/file/d/0B_WkX8bSkoT1QVR0WFJYdUY2SmZTdWdUVFNSM0F5WDF4YlBn/view

Screenshot of how it looks on different DPI screens:
https://screenshot.googleplex.com/ND5d9v0799y.png

Screenshot for RTL:
https://screenshot.googleplex.com/Xd3PyAYbDTV.png

BUG=634166
COMPONENT=Touch Calibration, ChromeOS, UI Strings

Review-Url: https://codereview.chromium.org/2600213002
Cr-Commit-Position: refs/heads/master@{#443000}