Load CouchbaseClientFactory via reflection to prevent ClassLoaderIssues when
the couchbase-client jar is not available.

Completes commit 300477e5d5b8fe9431f5bf0e38e85280c15c1509
Refs issue #177
After testing without couch base client libs, see that static class loader depend not gone.
Now I use reflect API to call CouchbaseClientFactory and it works!
Reset attributesAccessed to false on MemcachedBackupSession.recycle()
merge couchbase client patch without reflect usage