customer dropdown in edit-project

config.sample.json

@@ -7,6 +7,7 @@
     "groups": "http://localhost:8000/groups/",
     "joboffers": "http://localhost:8000/job-offers/",
     "projects": "http://localhost:8000/projects/",
+    "customers": "http://localhost:8000/customers/",
     "skills": "http://localhost:8000/skills/",
     "users": "http://localhost:8000/users/"
   }