Suggestion: add JSON.stringify to post if data is a JSON object and contentType is 'application/json'

[rw3iss]

Currently, if a json object is sent as data, it will url-encode the object.
If the server expects JSON, this will kill the request.
Reqwest includes the option to 'processData = false' within the request, but this leaves a JSON object being sent as [object Object].
This should be especially true of the contentType property is set to application/json, otherwise why would we send a url-encoded value if we are telling it to send json?

It would be nice to add an option to stringify a json object instead of url-encoding it, or otherwise auto-detect the application/json contentType and stringify the json object.

I added this in the code (without the option, just an object and contentType check),
in reqwest.js, line 203 inside getRequest():

  function getRequest(fn, err) {
    var o = this.o
      , method = (o['method'] || 'GET').toUpperCase()
      , url = typeof o === 'string' ? o : o['url']
      // convert non-string objects to query-string form unless o['processData'] is false
      , data = (o['processData'] !== false && o['data'] && typeof o['data'] !== 'string')
        ? (typeof o['data'] == 'object' && o['contentType'] == 'application/json') ? JSON.stringify(o['data']) : reqwest.toQueryString(o['data'])
        : (o['data'] || null)
      , http
      , sendWait = false

    ...

If anyone doesn't see an objection to this, I'll add it as a pull request.