Accept int as map key too

[BYK]

Accept integers in severity map too since when you pass the following

"text": {
    "type": "text",
    "include": "(\\.*)",
    "severity": {
        "3": "advice"
    }
}

to .arclint it throws an error. Reason is json_decode or PHP itself implicitly casting "3" into an integer 3.

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[BYK]

Thank you for your pull request and welcome to our community. We require contributors to sign our Contributor License Agreement, and we don't seem to have you on file. In order for us to review and merge your code, please sign up at https://code.facebook.com/cla - and if you have received this in error or have any questions, please drop us a line at cla@fb.com. Thanks!

Been there done that :)

[epriestley]

Bleh. Thanks. Cherry-picked as b4e91e1.