Added Web Store Sample App
Added assets and fixed nits
Added Web Store Edit URL to each project card
Added error console
Merge pull request #216 from GoogleChrome/addWebStoreSampleApp

Add web store sample app
changed calculator sample to use CSS instead of fixed images; removed 300ms delay on button clicks; allow calculator window to resize, using flexboxes
fixed name of web-store screenshot
Added web-store sample to README.md
fixed web-store tryme button