=doc #3682 Document message size limit in SslTlsSupport.
=act 3571 quiet down exceptions from `Socket.shutdownOutput()`

Backport from this spray commit:

https://github.com/spray/spray/commit/e4068046a5a501b059e0cf9305a85f9c1aca7e42
=act 3684 prevent usage of WriteCommands other than Tcp.Write with SslTlsSupport
Merge pull request #1798 from akka/wip-3682-document-message-size-limit-in-ssltlssupport-ban

=doc #3682 Document message size limit in SslTlsSupport.
Merge pull request #1804 from jrudolph/i/3684/prevent-WriteFile-CompoundWrite-in-ssl

=act 3684 prevent usage of WriteCommands other than Tcp.Write with SslTlsSupport
Merge pull request #1800 from jrudolph/i/3571/fix

=act 3571 quiet down exceptions from `Socket.shutdownOutput()`
Merge remote-tracking branch: upstream/master