change overrideTTL to overrideMaxAgeMs

Hello @x-ma,

There's also a change where you still have to call `.connect()` on the
in-memory cache to stay "api-compliant"

f20fec5f7eaf07138d9ddfe20160701982d01ac8 (2013-08-02 13:06:09 -0700)
change overrideTTL to overrideMaxAgeMs


R=@x-ma