Added the ability to call the api for a list of endpoints

This will now return a json response like:

{
 "get_device": "http://127.0.0.1:8080/api/v0/devices/:hostname",
 "get_vlans": "http://127.0.0.1:8080/api/v0/devices/:hostname/vlans",
 "get_graph_generic_by_hostname": "http://127.0.0.1:8080/api/v0/devices/:hostname/:type",
 "get_port_stats_by_port_hostname": "http://127.0.0.1:8080/api/v0/devices/:hostname/ports/:ifname",
 "get_graph_by_port_hostname": "http://127.0.0.1:8080/api/v0/devices/:hostname/ports/:ifname/:type",
 "list_devices": "http://127.0.0.1:8080/api/v0/devices",
 "add_device": "http://127.0.0.1:8080/api/v0/devices",
 "del_device": "http://127.0.0.1:8080/api/v0/devices/:hostname"
}