composer.json: renommage du module.

composer.json

 {
-    "name": "unicaen/unicaen-app",
-    "description": "Module commun aux applis ZF2 de l'UCBN",
+    "name": "unicaen/app",
+    "description": "Module de base des applications unicaen",
     "require": {
         "php":                                  ">=5.6 || >=7.0",
         "zendframework/zend-http":              "2.4.*",