API client connector

[rhuss]

This epic (scenario) is about a general purpose API Client Connector and the idea of a Connector Builder which can create a connector from a given API description (Swagger) and knows how to deal with OAuth flows in a generic fashion.

@kcbabo please fill in a more complete description of the business case, ideally again in the form of a narrative, including a concrete API which should be tackled first

The details needs to be flashed out in engineering planning meetings. The high-level list was assembled in the F2F Kickoff in Westford and highlights the topics

• Swagger (P0)
• OAS (P1)
• API Connector Builder (P0)
• OAuth Config (P0)
• API Connection Config (P0)
• Action Mapping based on Swagger (P0)
• Data Shape based on Swagger (P0)
• Headers and Query params - how handled (0)
   
  Comments:

• UI - General Settings -> API Connection Builder
• PoC for Swagger + OAuth ingest to
• Swagger-like view of resources for action list

[sjcox-rh]

Designs for issue found here:

syndesisio/syndesis-ux#49

Please review!
@dongniwang @amysueg @rhuss @gashcrumb @kahboom @kcbabo