Follow Up on EZEE-988 to support cluster setup of:

• eZ Platform (open source and ee)
• eZ Platform with legacy bridge (pending official support for that in EZEE-1455)

on Platform.sh.

Cluster implies:

• Redis/memcached support (done)
• Fastly support (Need Bundle to extend kernel and ezplatform-http-cache package for the misc iterations of our HttpCache integrations)
• Solr 6 support (done, but some sharding bug on platform.sh specifically, found by community user but not yet reported to us)