Update TransmissionRPC.class.php

moved rpc_version check before return_as_array inside the TransmissionRPC class constructor.
The program was attempting to obtain information from an object after it had been converted to a string.
Merge pull request #20 from odracir123/patch-1

Constructor would fail while fetch version if return_as_array=true

Move the rpc_version fetch before our initialization of return_as_array (leaving it with the default 'false'), sidestepping the issue.