rename struct OpenControl to Workspace/ LocalWorkspace

[jcscottiii]

In order to make more sense of the structs and their names and function, we should rename OpenControl to Workspace / LocalWorkspace.

To the external user of the go code, if they import the code. It's not obvious what OpenControl means. Also, right now it represents the in-memory data for all the collected resources via the get command which essentially creates a workspace.

And rename things like NewOpenControl to NewWorkspace

• Also, the concrete instance struct should be LocalWorkspace - Rename opencontrol to workspace #206 @jcscottiii
• LocalWorkspace should implement an interface called Workspace.

That interface will have methods like:

// not the exact code interface but just a rough idea
type Workspace interface {
   GetComponents() Components // return the interface of Components which needs to be done.
   GetCertifications() Certifications // return the interface of Certifications which needs to be done.
  ... // and so on
}

So... Why have an interface and struct? It makes it easier for external projects to use the interface in tests. Instead of 1) having to load same fixture data from this repo in their project or 2) having to import all the concrete structs and their different versions (e.g. different component.yaml versions), they can just use the interface and mock it with https://godoc.org/github.com/stretchr/testify/mock

[jcscottiii]

Closed by #226