Add application name to connections

[shueybubbles]

Fixes #189

[shueybubbles]

By updating to go-mssqldb v0.20.0 and adding app name to the connection string we will have both fields populated in sys.dm_exec_sessions

select program_name, client_interface_name from sys.dm_exec_sessions where session_id=62

program_name                   client_interface_name
------------------------------ ------------------------------
sqlcmd                         go-mssqldb

[stuartpa]