Added clear example

Notification will go away after 3 seconds
Updated screenshots Rich notifications
Fixed indents
Update window.html
Merge https://github.com/GoogleChrome/chrome-app-samples
Added clear option to all notifications
fixed indent
indext
Merge remote-tracking branch 'upstream/master'
Added auto clear to all notification types
Update window.html
Update main.js
Update main.js
Update window.html
spaces to tabs
Progress loops from 10-100
Revert "Progress loops from 10-100"

This reverts commit 48cfda0fcd4ed46ed477d79e3d213950da2fccef.
Merge pull request #223 from fvant/progressloop

Added auto clear option for all notifications