Fixed Web API calls without key

See koraktor/steam-condenser#219
Add test for Web API without key
Fix the name of Dota 2 Test inventory class
Add a CHANGELOG entry for logging
Make RCON termination conditional

Only non-empty RCON replies will be accompanied by a termination
request. This will prevent timeouts during `changelevel` and similar
commands.

See koraktor/steam-condenser#221
Update changelog for version 1.3.7
Version bump to 1.3.7
Merge branch '1.3-stable'