ref(data): implementing versions for real

This PR does the following:

Implements a working version of the (github.com/deis/workflow-manager/data/availableVersionsFromAPI).Refresh function that actually makes requests to the versions server.
Moves the code in the github.com/deis/workflow-manager/components package into the github.com/deis/workflow-manager/data package

This work was previously completed in #37 as part of a bigger refactor. That refactor has since been split into multiple PRs, culminating with this one.

Depends on #49 Closes #37

deis / workflow-manager

ref(data): implementing versions for real #42