Added Instagram provider

Added provider definition for Instagram
Added instagram to the table
Merge pull request #15 from msurguy/master

Added instagram to the providers and added a new row to readme
Added LinkedIn to the providers
Added Linkedin to the Table and the list of providers
Added Microsoft to the providers

Added auth provider for Microsoft accounts
Added Microsoft to the table of providers
Merge pull request #17 from msurguy/master

Added Linkedin and Microsoft to the providers
Merge pull request #18 from bitinn/master

github user might not have a display name