Make wfForeignMemcKey consistent with wfMemcKey

The wfMemcKey function converts any spaces in the key into _, while
the wfForeignMemcKey does not.  As such they would not return the same
key in certain corner cases.

Change-Id: I520dacdce953414dee5907324c2c98db858bcd42
Merge "Make wfForeignMemcKey consistent with wfMemcKey"