Create TcpListener class hierarchy from HttpListener classes

This issue fulfills task 2.1.b of Bulk LeaseQuery:

2. LeaseQueryListener
    2.1 Create the initial class hierarchy from CmdHttpListener hierarchy
    ...
       b. HttpListener* -> TcpListener*, these classes could reside in asiolink and possibly also be used
       as base classes for Http code, though this would be ancillary to making BLQ work.