vitastor-cli: add commands to control pools: pool-create, pool-ls, pool-modify, pool-rm

PR #59 - https://github.com/vitalif/vitastor/pull/58/commits

By MIND Software LLC

By submitting this pull request, I accept Vitastor CLA

src/cli_rm.cpp

@@ -245,6 +245,7 @@ resume_8:
         }
         state = 100;
         result = (cli_result_t){
+            .err = 0,
             .text = "",
             .data = my_result(result.data),
         };