clearer errors

"Not found" should only be for http path/method not found (404)
if it's about specific resources, we should be explicit for clarity

pkg/models/dashboards.go

@@ -11,6 +11,7 @@ import (
 // Typed errors
 var (
 	ErrDashboardNotFound           = errors.New("Dashboard not found")
+	ErrDashboardSnapshotNotFound   = errors.New("Dashboard snapshot not found")
 	ErrDashboardWithSameNameExists = errors.New("A dashboard with the same name already exists")
 	ErrDashboardVersionMismatch    = errors.New("The dashboard has been changed by someone else")
 )

pkg/models/models.go

@@ -1,7 +1,5 @@
 package models
 
-import "errors"
-
 type OAuthType int
 
 const (
@@ -9,5 +7,3 @@ const (
 	GOOGLE
 	TWITTER
 )
-
-var ErrNotFound = errors.New("Not found")