Wrong Error Message When Node Running on Older Version of Protocol

Describe the bug Minor bug - I think we can improve our error message for this common mistake of trying to run the newest node on an older version of the protocol.

To Reproduce Steps to reproduce the behavior:

1. Try to launch the CLI for a PM-compatible broadcasting node on the current Rinkeby contract.

Screenshots

+-----------+
|NODE STATS|
+-----------+
*-----------------------------*--------------------------------------------*
|                   HTTP Port |                                       7935 |
*-----------------------------*--------------------------------------------*
|          Controller Address | 0x37dC71366Ec655093b9930bc816E16e6b587F968 |
*-----------------------------*--------------------------------------------*
|       LivepeerToken Address | 0x24f56eF2fED379421BEE64Ecafc2bC744f72522b |
*-----------------------------*--------------------------------------------*
| LivepeerTokenFaucet Address | 0xD69A2eC8f2F83267CE82A6d01837045BaE0EB9Bc |
*-----------------------------*--------------------------------------------*
|                 ETH Account | 0xf73580a0D020870Fdc2B6bde65235F57acf39FCC |
*-----------------------------*--------------------------------------------*
|                 LPT Balance |                                          0 |
*-----------------------------*--------------------------------------------*
|                 ETH Balance |                                          0 |
*-----------------------------*--------------------------------------------*
+-----------------+
|BROADCASTER STATS|
+-----------------+
ERROR: logging before flag.Parse: E0117 15:50:00.077154   16559 wizard_stats.go:123] Error getting sender info: invalid character 'c' looking for beginning of value
^C

On B:

I0117 15:49:40.084376   16551 mediaserver.go:115] Transcode Job Price: 1, Transcode Job Type: [{P240p30fps16x9 600k 30 426x240 16:9} {P360p30fps16x9 1200k 30 640x360 16:9}]
I0117 15:49:40.084488   16551 lpms.go:97] HTTP Server listening on http://127.0.0.1:8935
I0117 15:49:40.084497   16551 lpms.go:90] LPMS Server listening on rtmp://127.0.0.1:1935
E0117 15:49:48.320920   16551 handlers.go:24] HTTP Response Error 500: could not query sender info: ErrNoResult