Figure out and fix "Problem accessing SSM parameters" on PROD runs

[mathomas]

We get this exception every production run, but then it continues to operate normally. Should be fixed, since it's a false alarm.

2018-07-12T19:55:15.640Z	7e7abd67-860d-11e8-872e-a1cab863f08b	Problem accessing SSM parameters for /slink/PROD Error: Configuration value not found in SSM Parameter Store for: /slink/PROD/undefined
at keys.forEach (/var/task/config.js:90:15)
at Array.forEach (<anonymous>)
at Object.loadConfigParams (/var/task/config.js:83:10)
at <anonymous>
at process._tickDomainCallback (internal/process/next_tick.js:228:7)