Fixed bmp image previewing/uploading by adding new go image library

Godeps/Godeps.json

@@ -151,6 +151,10 @@
 			"ImportPath": "gopkg.in/redis.v2",
 			"Comment": "v2.3.2",
 			"Rev": "e6179049628164864e6e84e973cfb56335748dea"
+		},
+		{
+			"ImportPath": "golang.org/x/image/bmp",
+			"Rev": "eb11b45157c1b71f30b3cec66306f1cd779a689e"
 		}
 	]
 }

api/file.go

@@ -15,6 +15,7 @@ import (
 	"github.com/nfnt/resize"
 	"image"
 	_ "image/gif"
+	_ "golang.org/x/image/bmp"
 	"image/jpeg"
 	"io"
 	"net/http"