Add commonjs unit testing unit tests

[JakeChampion]

Fixes #35

[JakeChampion]

2 failing tests from the new test suite:

  1) commonjs unit testing unit tests converted to mocha test deepEqual "" [""]:

      AssertionError: [Function] throws [Function: AssertionError]
      + expected - actual


      at Function.proclaim.throws (lib/proclaim.js:66:13)
      at Context.exports.test deepEqual "" [""] (test/unit/commonjs-assert/program.js:129:19)

  2) commonjs unit testing unit tests converted to mocha test throw AssertionError:

      AssertionError: type
      + expected - actual

      -false
      +true

      at Function.ok (lib/proclaim.js:14:13)
      at Context.exports.test throw AssertionError (test/unit/commonjs-assert/program.js:156:11)

[rowanmanning]

This looks good, thanks @JakeChampion. Gonna investigate fixing these issues before merging

I've made a lot of changes since the review

[rowanmanning]

Few small comments

[rowanmanning]

Is this supposed to be notDeepStrictEqual?

[rowanmanning]

Removal of this whitespace messes up README formatting. Could you add back or replace with an actual <br/>? I've been meaning to for ages 😅

Made the changes requested by the reviewer, please re-review.