Fix getImagesJSON output for api less than 1.7

Tag can be a number, like centos:6.4, and so must be handled like a
string otherwise will lose quotation marks when converting to json
and the client (API < 1.7) will try to convert to int, failing
because the type is string. Additionally using ParseRepositoryTag to
parse repository names to split the tag because an URL can have : and
so more than one occurrence of : can be found on repository names.

Docker-DCO-1.1-Signed-off-by: Fabio Falci <fabiofalci@gmail.com> (github: fabiofalci)

api/server/server.go

@@ -238,10 +238,10 @@ func getImagesJSON(eng *engine.Engine, version version.Version, w http.ResponseW
 		outsLegacy := engine.NewTable("Created", 0)
 		for _, out := range outs.Data {
 			for _, repoTag := range out.GetList("RepoTags") {
-				parts := strings.Split(repoTag, ":")
+				repo, tag := utils.ParseRepositoryTag(repoTag)
 				outLegacy := &engine.Env{}
-				outLegacy.Set("Repository", parts[0])
-				outLegacy.Set("Tag", parts[1])
+				outLegacy.Set("Repository", repo)
+				outLegacy.SetJson("Tag", tag)
 				outLegacy.Set("Id", out.Get("Id"))
 				outLegacy.SetInt64("Created", out.GetInt64("Created"))
 				outLegacy.SetInt64("Size", out.GetInt64("Size"))