Capitalize isEdgeDevice in new device request model

[elvinm]

Type of change?

• [x] Bug fix
• [ ] New feature
• [ ] Enhancement
• [ ] Breaking change (breaks backward compatibility)

Description, Context, Motivation

The Java version of iothubmanager fails to create a new edge device properly because it expects the json model to send the same case as it appears in the backend.

This should be capitalized as it appears in all of our other device model properties. ...

Checklist:

• [x] All tests passed
• [x] The code follows the code style and conventions of this project
• [ ] The change requires a change to the documentation
• [ ] I have updated the documentation accordingly

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This change is