Calculator: fits on Emulator screen

* Horizonally centered & width limited to 550px
* Vertically limited to 665px, but not centered because of Emulator quirk

Open-WebOS-DCO-1.0-Signed-Off-By: [Doug Reeder] <reeder_29@yahoo.com>
Merge pull request #2 from DougReeder/master

Calculator: fits on Emulator screen