Add user lookup to ldapserver ping

This should help keep the cache fresh so create user requests don't time
out when people go to sign up.

ldapserver/server.py

@@ -21,6 +21,7 @@ def index():
 
 @app.route('/ping')
 def ping():
+    ldap_functions.find_user('tanner.collin')
     return 'pong'
 
 @app.route('/find-user', methods=['POST'])