Replacing the obsolete links

Using the Webarchive, I found that the new location for "http://www.shopify.com/developers/publishing" is "http://docs.shopify.com/partners/partner-resources/for-partners/building-a-shopify-app"
Also, the twitter account of https://twitter.com/shopifyapi is moved to https://twitter.com/shopifydevs
Merge pull request #107 from afshing/patch-1

Replacing the obsolete links