Replace deprecated tc7 getSessionCookieName with new one.
Update spymemcached to 2.10.2 and couchbase-client to 1.2.2

The password now has to be passed as empty string to the couchbaseclient,
because it refuses to accept null.
Extract memcached/couchbase client setup to factories to make dependency on couchbase jars optional.

Fixes #177: msm requires couchbase jars even when not using couchbase