[WIP] Blueprint tests

[kimroen]

Fixes #101

[kimroen]

Added some tests where one of them should fail just to check that everything is all right, but then they both passed.

[trabus]

You're using the wrong property to check the file, it should be contains, not contents:

files (array): Array of files to assert, represented by objects with file, exists, contains, or doesNotContain properties. Example object:

files: [
  {
    file: 'path-to-file.js', 
    contains: ['file contents to compare'], 
    doesNotContain: ['file contents that shouldn\'t be present'], 
    exists: true //default true
  }
]```

[trabus]

Should be contains here

[kimroen]

I came back to take a look at this today, but so much had happened with the blueprint test helpers that I figured it would be better to start over. I did that over here: #129

Thanks for the help!