Code hygiene - Rubocop offences

[mhudson]

rubocop --require rubocop-rails --require rubocop-rspec --format offenses lists nearly 500 offences.

Address each by type, and raise a PR for each of the larger issues. Smaller issues can be grouped into a single PR.
Specs must still pass before submitting the PR.

---

138 Style/Documentation
51 Metrics/MethodLength
35 Metrics/AbcSize
33 RSpec/InstanceVariable
24 RSpec/BeforeAfterAll
22 Rails/HasManyOrHasOneDependent
20 Rails/ReversibleMigration
18 RSpec/MultipleExpectations
16 Naming/InclusiveLanguage
16 RSpec/ExampleLength
14 Metrics/BlockLength
13 Lint/UselessAssignment
12 Rails/BulkChangeTable
12 Rails/Date
9 Rails/InverseOf
6 Metrics/ClassLength
5 Metrics/PerceivedComplexity
5 RSpec/EmptyExampleGroup
4 Lint/UnreachableCode
4 Metrics/CyclomaticComplexity
4 RSpec/ScatteredSetup
3 Naming/PredicateName
3 RSpec/DescribeClass
3 RSpec/FilePath
3 RSpec/NamedSubject
3 Rails/FilePath
3 Style/GuardClause
2 Lint/DuplicateBranch
2 Lint/RescueException
1 Lint/ConstantDefinitionInBlock
1 Lint/EmptyBlock
1 Lint/EmptyConditionalBody
1 Lint/SuppressedException
1 RSpec/ContextWording
1 RSpec/MessageSpies
1 RSpec/StubbedMock
1 Rails/CreateTableWithTimestamps
1 Rails/HasAndBelongsToMany
1 Rails/LexicallyScopedActionFilter
1 Rails/UniqueValidationWithoutIndex

494 Total