Remove unneeded vendor dependencies

.gitmodules

@@ -1,6 +1,6 @@
 [submodule "vendor/github.com/pkg/errors"]
 	path = vendor/github.com/pkg/errors
 	url = https://github.com/pkg/errors
-[submodule "vendor/golang.org/x"]
-	path = vendor/golang.org/x
-	url = https://golang.org/x
+[submodule "vendor/golang.org/x/image"]
+	path = vendor/golang.org/x/image
+	url = https://golang.org/x/image

process.go

@@ -78,7 +78,7 @@ func (p *Processor) Resize(img *image.NRGBA) (image.Image, error) {
 		pw := c.Width - int(float64(c.Width)-(float64(p.NewWidth)/100*float64(c.Width)))
 		ph := c.Height - int(float64(c.Height)-(float64(p.NewHeight)/100*float64(c.Height)))
 		if pw > newWidth || ph > newHeight {
-			err := errors.New("the generated image size should be less than original image size.")
+			err := errors.New("The generated image size should be less than original image size.")
 			return nil, err
 		}
 		// Reduce image size horizontally