Support running a whole flow specified using a .flow file with the Go API

[senthilmk]

Right now, the Go API has limited support running a whole flow from a .flow file (Supports only specifying Resources, but not Triggers in the .flow file)

The Go API needs to support running the whole flow (Triggers, Resources) that is defined in the flow file. In essence provide a declarative approach based API for use in integration based scenarios