Specify "application/json" content-type for POST/PUT requests

[dhritzkiv]

For certain POST and PUT requests, this specifies the content type as "application/json" (instead of the oauth module's default "application/x-www-form-urlencoded"). This seems to fix "signature invalid" errors.

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Around the start of September, requests to Shapeways were failing because of "invalid signature" errors, this commit seems to fix those issues.

Note: this was only tested for the addModel method (as it's the only one I'm using), but it should apply to all requests that had JSON.stringify called on a javascript object and passed as the body argument.

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Closes #7

This was made possible using the suggestions made by @imdaveho and @RandomCouch. Thanks you two!

[coveralls]

Coverage decreased (-3.3%) to 93.258% when pulling 2213d18 on dhritzkiv:patch-2 into 5116d3f on Shapeways:master.

[coveralls]

Coverage decreased (-3.3%) to 93.258% when pulling 2213d18 on dhritzkiv:patch-2 into 5116d3f on Shapeways:master.

[coveralls]

Coverage decreased (-3.3%) to 93.258% when pulling 0874632 on dhritzkiv:patch-2 into 5116d3f on Shapeways:master.

[coveralls]

Coverage increased (+0.1%) to 96.629% when pulling 18b8682 on dhritzkiv:patch-2 into 5116d3f on Shapeways:master.

[d33psky]

Looks good. thanks.

[peter-rybar]

@d33psky, thank you for merge. Can you update NPM package also? Thank you in advance.

[dhritzkiv]

@d33psky bump! for release attention

[dhritzkiv]

@peter-rybar, in the meantime, you can set the value of "shapeways" in your package.json to "git+ssh://git@github.com:Shapeways/node-shapeways.git#9d0a5a4e90dda958061a0973357700eb28b5ce79" to target the repo's current state