Add basic application framework and example application to show interaction between events an NBI

Depends on:

• !340 (merged)
• !344 (merged)
• !349 (merged)
• !342 (merged)

controller/topology/ports/configuration/configuration.go

+package configuration
+
+import (
+	"fmt"
+	"net"
+)
+
+type IPConfig struct {
+	IP           net.IP `json:"ip,omitempty"`
+	PrefixLength int    `json:"prefix_length,omitempty"`
+}
+
+func New(ip string, prefixLength int) (IPConfig, error) {
+	newIPConfig := IPConfig{}
+	parsedIP := net.ParseIP(ip)
+	if parsedIP == nil {
+		return newIPConfig, fmt.Errorf("%s can not be parsed to an IP.", ip)
+	}
+
+	newIPConfig.IP = parsedIP
+	newIPConfig.PrefixLength = prefixLength
+
+	return newIPConfig, nil
+}