directory structure change to work with glide

glide has its own requirements. My previous workaround caused me some
code checkin errors. Need to fix this.

weed/server/filer_server.go

@@ -0,0 +1,67 @@
+package weed_server
+
+import (
+	"net/http"
+	"strconv"
+
+	"github.com/chrislusf/seaweedfs/weed/filer"
+	"github.com/chrislusf/seaweedfs/weed/filer/cassandra_store"
+	"github.com/chrislusf/seaweedfs/weed/filer/embedded_filer"
+	"github.com/chrislusf/seaweedfs/weed/filer/flat_namespace"
+	"github.com/chrislusf/seaweedfs/weed/filer/redis_store"
+	"github.com/chrislusf/seaweedfs/weed/glog"
+	"github.com/chrislusf/seaweedfs/weed/security"
+)
+
+type FilerServer struct {
+	port               string
+	master             string
+	collection         string
+	defaultReplication string
+	redirectOnRead     bool
+	disableDirListing  bool
+	secret             security.Secret
+	filer              filer.Filer
+}
+
+func NewFilerServer(r *http.ServeMux, ip string, port int, master string, dir string, collection string,
+	replication string, redirectOnRead bool, disableDirListing bool,
+	secret string,
+	cassandra_server string, cassandra_keyspace string,
+	redis_server string, redis_password string, redis_database int,
+) (fs *FilerServer, err error) {
+	fs = &FilerServer{
+		master:             master,
+		collection:         collection,
+		defaultReplication: replication,
+		redirectOnRead:     redirectOnRead,
+		disableDirListing:  disableDirListing,
+		port:               ip + ":" + strconv.Itoa(port),
+	}
+
+	if cassandra_server != "" {
+		cassandra_store, err := cassandra_store.NewCassandraStore(cassandra_keyspace, cassandra_server)
+		if err != nil {
+			glog.Fatalf("Can not connect to cassandra server %s with keyspace %s: %v", cassandra_server, cassandra_keyspace, err)
+		}
+		fs.filer = flat_namespace.NewFlatNamespaceFiler(master, cassandra_store)
+	} else if redis_server != "" {
+		redis_store := redis_store.NewRedisStore(redis_server, redis_password, redis_database)
+		fs.filer = flat_namespace.NewFlatNamespaceFiler(master, redis_store)
+	} else {
+		if fs.filer, err = embedded_filer.NewFilerEmbedded(master, dir); err != nil {
+			glog.Fatalf("Can not start filer in dir %s : %v", dir, err)
+			return
+		}
+
+		r.HandleFunc("/admin/mv", fs.moveHandler)
+	}
+
+	r.HandleFunc("/", fs.filerHandler)
+
+	return fs, nil
+}
+
+func (fs *FilerServer) jwt(fileId string) security.EncodedJwt {
+	return security.GenJwt(fs.secret, fileId)
+}