Locations Model

[alexander-mathieu]

Changes proposed in this pull request:

• Adds Location model (belongs to User)
• Adds User has one Location
• Adds Dog has one Location through User
• Adds specs for all new relationships
• Adds LocationType to GraphQL interface with attributes
• Adds location attribute to UserType
• Updates user/users query specs with location attribute assertions
• Adds seeds for Location model

Resolves #42, resolves #39

The following checks have been completed:

• [x] Tested my new feature(s) as well as any feasible edge cases (if possible)
• [x] Checked coverage/index.html - did not add any new code that's not covered by testing (if possible)
• [x] Merged in the latest master to my branch with git pull origin master & resolved merge conflicts
• [x] Ran rails db:migrate
• [x] Ran the test suite - all tests are passing (or maybe skipped)
• [x] Checked affected endpoints in Postman / GraphiQL
• [x] Updated README for changes (new endpoints, new gems, etc)

[chakeresa]

Let's add LocationType to the README.