fixed name of web-store screenshot
Added web-store sample to README.md
fixed web-store tryme button
[hello-world] Bumped manifest version
bumped calculator version
Merge branch 'master' of github.com:GoogleChrome/chrome-app-samples
[web-store] Updated key to reflect the one from the published app
Merge https://github.com/GoogleChrome/chrome-app-samples
Added clear option to all notifications