server: close TCP connection after CloseConnection event

[belm0]

Fixes #115 and #147.

[belm0]

I have no idea what I'm doing-- but this change fixes the shutdown issue with asyncio client, and fixes all of the broken autobahn tests.

If this change is OK I should add a unit test. (done)

@njsmith does this one line change look harmful?

[coveralls]

Pull Request Test Coverage Report for Build 163

• 2 of 2 (100.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.02%) to 95.761%

---

Totals
Change from base Build 155:	0.02%
Covered Lines:	497
Relevant Lines:	519

---

💛 - Coveralls