You don't need bitcoind for blocchain.info's RPC API, that was just to verify that everything (aside from your code) works. Something about the wrapper or the way you're performing the web request is causing your problem.
Their API does support the "verifymessage" command, scroll down to the bottom of the documentation page for the info:
Method: verifymessage
Parameters: (String bitcoinaddress, String signature, String message)
Description: Verifies the signature and message matches the bitcoin address provided (See signmessage)
Returns: Boolean
Also, you may want to take a look at this thread for verifying messages offline (without bitcoind), with libraries for several different languages:
https://bitcointalk.org/index.php?topic=222992.0