refs #71 auto evict implementation, squash commit from gh71

Auto eviction is enabled by setting evs.auto_evict value greater
than zero and evs.version to 1.
refs #71 auto evict implementation, squash commit from gh71

Auto eviction is enabled by setting evs.auto_evict value greater
than zero and evs.version to 1.
Merge branch '3.x-gh71' of github.com:codership/galera into 3.x-gh71
Merge pull request #155 from codership/3.x-gh71

refs #71, #155 auto evict implementation
 Merge galera-3.x upto 1dd46ba6ad34775e0d8e11743b01c4625709853f