Replace Mockery with Phony

[shadowhand]

The expect-run-verify model of testing does not mirror how code is
actually developed. A mock-run-verify approach allows faster prototyping
and reflects how code is actually executed.

Phony has additional features, such as order verification.

https://github.com/eloquent/phony#inception

[coveralls]

Coverage remained the same at 100.0% when pulling eff6d89 on feature/replace-mockery-with-phony into 04a2612 on 2.x.

[shadowhand]

@ramsey any objections to this change?

[coveralls]

Coverage remained the same at 100.0% when pulling 22c3cb7 on feature/replace-mockery-with-phony into 0958ebd on 2.x.

[coveralls]

Coverage remained the same at 100.0% when pulling 2aa6980 on feature/replace-mockery-with-phony into 0958ebd on 2.x.

[ramsey]

@shadowhand No objections. Looks good.

[coveralls]

Coverage remained the same at 100.0% when pulling 1c58178 on feature/replace-mockery-with-phony into 0958ebd on 2.x.

[coveralls]

Coverage remained the same at 100.0% when pulling 1c58178 on feature/replace-mockery-with-phony into 0958ebd on 2.x.

[coveralls]

Coverage remained the same at 100.0% when pulling 1c58178 on feature/replace-mockery-with-phony into 0958ebd on 2.x.