Servefile

* improved test performance

* fixed bug where exception was shown on transmission abort with python3
* fixed wrong/outdated pyopenssl package names
* tests are now using a free non-default port to avoid clashes; if
wished the ports can be set from outside by specifying the
environment variables SERVEFILE_DEFAULT_PORT and
SERVEFILE_SECONDARY_PORT
* fixed broken redirect when filename contained umlauts or other characters
that should have been quoted
* fixed broken special char handling in directory listing for python2
* drop python3.5 support
* fixed PUT uploads with python3 and documented PUT-uploads with curl

* version bump for broken pypi release

* python3 support
* test suite
* fixed an endless redirect loop when serving ../
* added sorting for list view
* added lzma/xz as compression method

* prefer using TLS1.2/TLS1 with --ssl if available
* issue v3 certificates for self signed certificates with --ssl
* removed lots of unnecessary error output
* fixed a bug where wrong ranges were used on a HEAD request in directory listing mode
* fixed a bug where directory listing mode allowed path traversal

* display user/password in url-list when authentication is used
* various directory-listing patches by Sebastian Pipping
* case-insensitive sorting
* sort directories to top
* hide .. in top directory
* better error reporting/exception handling patch by Robert Buchholz
* properly tell clients that http keep-alive is not available