Creates a new user object on database
		Returns the User Object. Must be linked to a new trainer soon after

def create_user(self, username, first_name=None, last_name=None):
		"""
		Creates a new user object on database
		Returns the User Object. Must be linked to a new trainer soon after
		"""
		
		url = api_url+'users/'
		payload = {
			'username':username
		}
		if first_name:
			payload['first_name'] = first_name
		if last_name:
			payload['last_name'] = last_name
		r = requests.post(url, data=json.dumps(payload), headers=self.headers)
		print(request_status(r))
		r.raise_for_status()
		return User(r.json())