Meta issue: SDX-Controller API improvement: spec 2.0 and service enhancement

[YufengXin]

This is a list of issues to be addressed:

These two need modification of the endpoints in swagger.yaml

• SDX controller must have new endpoints according to specification 2.0 #299
• Support patch/change operation for an existing connection request #235

These need some work in the API control functions related to DB:

• Query connection event history #238
• SDX Controller should provide service accountability  #316
• Error handling when latest topology is not available in DB #172
• SDX-Controller should display vlan field for a connection/l2vpn instead of vlan_range #314
• SDX-Controller is not reporting the chosen VLAN when vlan is "any" #320
• SDX should sync topology update with LC #311
• Create an endpoint to list domains #312
• SDX-Controller should load the topology from DB when starting up #308
• Mark domain/link/port as impaired when state is unknow #313

These related to PCE possibly

• Creating a connection to a port directly attached to a neighbor domain results in wrong breakdown #309

Related to AA:

• SDX Controller User Authentication and Ownership #298