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/topology/configuration.go

@@ -0,0 +1,65 @@
+package topology
+
+import (
+	"encoding/xml"
+)
+
+type loc struct {
+	dcName   string
+	rackName string
+}
+type rack struct {
+	Name string   `xml:"name,attr"`
+	Ips  []string `xml:"Ip"`
+}
+type dataCenter struct {
+	Name  string `xml:"name,attr"`
+	Racks []rack `xml:"Rack"`
+}
+type topology struct {
+	DataCenters []dataCenter `xml:"DataCenter"`
+}
+type Configuration struct {
+	XMLName     xml.Name `xml:"Configuration"`
+	Topo        topology `xml:"Topology"`
+	ip2location map[string]loc
+}
+
+func NewConfiguration(b []byte) (*Configuration, error) {
+	c := &Configuration{}
+	err := xml.Unmarshal(b, c)
+	c.ip2location = make(map[string]loc)
+	for _, dc := range c.Topo.DataCenters {
+		for _, rack := range dc.Racks {
+			for _, ip := range rack.Ips {
+				c.ip2location[ip] = loc{dcName: dc.Name, rackName: rack.Name}
+			}
+		}
+	}
+	return c, err
+}
+
+func (c *Configuration) String() string {
+	if b, e := xml.MarshalIndent(c, "  ", "  "); e == nil {
+		return string(b)
+	}
+	return ""
+}
+
+func (c *Configuration) Locate(ip string, dcName string, rackName string) (dc string, rack string) {
+	if c != nil && c.ip2location != nil {
+		if loc, ok := c.ip2location[ip]; ok {
+			return loc.dcName, loc.rackName
+		}
+	}
+
+	if dcName == "" {
+		dcName = "DefaultDataCenter"
+	}
+
+	if rackName == "" {
+		rackName = "DefaultRack"
+	}
+
+	return dcName, rackName
+}