ALM-686 enable memcached cluster
ALM-686 adapted configuration
ALM-686 only manage workers if workers are specified in settings.yml
ALM-686 can't use rails variable in capistrano
ALM-686 provide number of workers as ENV variable
ALM-686 use ENV for workers
ALM-686 ENV is of type string
removed outdated code
fixed syntax error
ALM-686 allow to pass memcached_servers as ENV
ALM-625 import via CrossRef API