Adds delete Account functionality

[EndoSkeletor]

Resolves #213

[PululuK]

LGTM, thanks @EndoSkeletor
A small feedback :)

[PululuK]

Suggested change

	public function deleteAccount(string $account_id): \stdClass
	{
	$identifier = $account_id;
	$user = $this->adapter->delete('accounts/' . $identifier);
	$this->body = json_decode($user->getBody());
	return (object)['result' => $this->body->result];
	}
	public function deleteAccount(string $account_id): \stdClass
	{
	$user = $this->adapter->delete('accounts/' . $account_id);
	$this->body = json_decode($user->getBody());
	return (object)['result' => $this->body->result];
	}