Make json file RFC 4627 valid

[greglint]

I noticed the json file has a trailing comma where it shouldn't, and this is hitting my linter.

[ghost]

Your pull request doesn't follow our guidelines. Please fix the following:

• Pull request description cannot be empty (?)
• Pull request title must not end with a dot (?)

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[ghost]

This pull request still violates some of our guidelines:

• Pull request title must not end with a dot (?)

Click here for details.

[ghost]

Thank you, the title and description now looks good!

[greglint]

Hi @petems any chance of getting this merged? I don't think it can break anything, but the Travis CI builds failed for some reason :/

[petems]

@greglint The tests are failing for some weird reason, will merge this now 👍