Add MemcachedEngine
Fix coding standards
Coding standard fix
Drop backup/restore Configure values
Add support for Amazon ElastiCache
Remove unnecessary return
Throw an exception if attempting to use authentication without SASL support  installed
Coding standard and readability
Starting the memcached server on travis

To properly test the memcached cache engine
Merge pull request #1562 from kamisama/feature/2.5-memcached-cache-engine

2.5: Add Memcached storage engine for cache 

Fixes #3511