Revert "Temporarily remove explicit dependency on Evenement to fix install"

This reverts commit bcb7dbd.

Author: clue

composer.json

@@ -12,6 +12,7 @@
     ],
     "require": {
         "php": ">=5.3",
+        "evenement/evenement": "~1.0|~2.0",
         "react/promise": "~1.0|~2.0",
         "react/socket-client": "^0.5 || ^0.4 || ^0.3",
         "react/event-loop": "0.3.*|0.4.*"