User Story 7, Merchant Navigation

[BrianZanti]

As a merchant employee or admin
I see the same links as a regular user
Plus the following links:
- a link to my merchant dashboard ("/merchant")

DO THESE STORIES FIRST:

• User Story 6, User Navigation

Checklist:

• base tests are written
• base code is written to pass tests
• edge case ("sad path") tests written (if required)
• edge case code written (if required)
• code is reviewed
• branch is merged
• all tests still pass

child of #236

child of #242

depends on #234