HTTPSock: Gzip compression for static files (text/* mime types + files
with .js extension) and dynamic HTML responses (if gzip is available and
the compression method is supported by the requesting HTTP client).
Get rid of empty CHTTPSock::WriteFileGzipped method if there's no zlib. It's still in the header, but this does not have any negative side effects.
controlpanel.cpp: Increase verbosity of successful "Disconnect" command

This modifies line 897 to have more verbosity on the output for a successful execution of the "Disconnect" command, which will allow for the output to say what network was force-disconnected on what user.

This is a repaired version of pull request #352 which I closed after a FTBFS which I did not realize.
Merge pull request #353 from TheLordOfTime/patch-1

controlpanel.cpp: Increase verbosity of successful "Disconnect" command
Merge commit 'refs/pull/306/head' of github.com:znc/znc
webadmin: clarify that + is SSL