Convert to using Go modules

See merge request !17

- Update GitLab CI and Makefile.
- Remove `Gopkg.*` and `vendor/`.
- All test variations pass.

Improve table-driven tests to drive error checks by the test field, not the error result

See merge request !16

- Linter fixes.
- Sync `vendor/` for updated dependencies.
- All test variations pass.

Refactor excess relations in schema

See merge request !15

- Update migrations, models, store, controllers, and unit/integration tests.
- All test variations pass.

Convert model validation tests to table-driven tests

See merge request !14

- All test variations pass.

Sync vendor/ for updated dependencies

See merge request !13

Revamp linters

See merge request !12

- All test variations pass.

Update docker-compose and CI to use smaller, more secure Alpine variants

See merge request !11

- All test variations pass.

Update CI to use Golang Alpine image for building

See merge request !10

- Musl is a better libc.
- No change in build time.
- All test variations pass.

Tune configuration object revamp further

See merge request !9

- Break out service prefixes for env variables.
- More full-featured `test/random` package with seeding.
- All test variations pass.

Change pkg/config to use reflection-less env variable parsing

See merge request !8

- Add a support `test/random` package for generating random strings for tests.
- All test variations pass.

Update README.md badges to include CI status

See merge request !7

- Catch up formatting with `gofmt -s` that was missed by goreturns.
- All test variations pass.

Configure GitLab CI

See merge request !6

- All test variations pass.

- Required for CI.
- All test variations pass.

Convert from psql-based manual migrations to migrate command

See merge request !5

- Go-based migrations will significantly simplify CI.
- All test variations pass.

- Preferred for a more reliable `dep check`.

Remove superfluous app/ from the internal/ hierarchy

See merge request !4

- If it's shareable, it's good enough for `pkg/`.
- All test variations pass.

Convert project to standard Golang layout

See merge request !3

- Add `dep check` to `Makefile`'s lint target.
- All test variations pass.

- All test variations pass.

Begin converting integration tests to Go with docker-compose

See merge request !2

- Tune `Makefile` for faster builds.
- All test variations pass.

- Tune Makefile, README.md, and psql.
- All test variations pass.

Linter fixes

See merge request !1

- Use staticcheck and gometalinter via Makefile.
- Update integration tests with duplicate names.
- All test variations pass.

- All test variations pass.

- All test variations pass.