fn: rename from fnctl (#321)

* fn: rename from fnctl

* fn: predicting the release version for installer

* fn: predicting the release version for installer

fn/errors.go

@@ -0,0 +1,13 @@
+package main
+
+type notFoundError struct {
+	S string
+}
+
+func (e *notFoundError) Error() string {
+	return e.S
+}
+
+func newNotFoundError(s string) *notFoundError {
+	return &notFoundError{S: s}
+}