v2.0.0: OAuth 2.0 support

Adding OAuth 2.0 support

• Implement OAuth2 (Twitter2Strategy) by @na2hiro in #27 #28

Omitting API v1.1 usage from OAuth 1.0a

• Remove V1.1 verify_credentials call after successful token retrieval by @na2hiro in #26
• Breaking changes
  • Renamed the class TwitterStrategy → Twitter1Strategy
  • Renamed the default name twitter → twitter1 (should be no harm)
  • Renamed clientId, clientSecret → consumerKey, consumerSecret in the options to match the names in Twitter Developer Portal
  • Profile passed to verify function has only userId (numeric string) and screenName (string), instead of a big object with bunch of fields. You would need to call Twitter APIs yourself using the access token and access secret token. https://github.com/plhery/node-twitter-api-v2 is one of the client for API client for Twitter.

Full Changelog: v1.0.0...v2.0.0