Implement routes for getting, saving, and updating saved directions

[jkwening]

Complete routing for saved directions feature for the app. Currently the plan is to handle routes for this as part of the search feature so routing url endpoints should go into: ./routes/search.js module.

Overview of task:

• define getting, saving, updating, and deleting end points in ./routes/search.js for saved directions
  • make sure to pass verifyToken so end point is secure and requires authentication before proceeding - see savedpins routes as an example
• implement controller functions for end points in ./controllers/saved-directions-controller.js

Notes - initial model for storing saved directions data is in ./models/saved-directions.js; should consider adding feature for description/user defined labels for saved direction.

[jkwening]

closing in favor of more specific issues has frontend and backend start communicating.