Jd class

The first part of a C++ class to get / upload from isense.
Currently only pulls fields and posts using contributor keys.
In the future I'll add email / password support, as well as a few other API functions.
Requires picojson to make. Also, 'value' and 'object' are picojson objects.
@stowellm @bdonald25
What's the point of `" << "` here?  Couldn't this line be:
```
cout << "\nUploading to rSENSE.\n\n";
```