Merge pull request #3224 from gravitl/acls_cache_fix

initiliase acl cache

logic/acls.go

@@ -172,6 +172,9 @@ func InsertAcl(a models.Acl) error {
 func GetAcl(aID string) (models.Acl, error) {
 	a := models.Acl{}
 	if servercfg.CacheEnabled() {
+		if len(aclCacheMap) == 0 {
+			_ = listAcls()
+		}
 		var ok bool
 		a, ok = getAclFromCache(aID)
 		if ok {