another tiny simplification

Per: https://docs.python.org/2/library/functions.html#filter

filter(None, list) is equivalent to [item for item in iterable if item]
added URL-rewriting for http://

What it says on the tin.
added config option to append raw headers to response

code for handling this config option coming soon.
mild cleanup

little cleaner
added support for extra_http_response_headers

same as the previous patches.
Merge pull request #183 from virgil/patch-12

added URL-rewriting for http://
Merge pull request #182 from virgil/patch-11

another tiny simplification
Merge pull request #185 from virgil/patch-14

mild cleanup
Merge pull request #184 from virgil/patch-13

added config option to append raw headers to response
Add better documentation for extra_HTTP_headers_to_response
Merge pull request #191 from virgil/patch-19

added support for extra_http_response_headers
Merge branch 'master' of github.com:globaleaks/Tor2web-3.0
Remove wrong spaces and newlines
manual integration of virgil patch to extra_http_response_headers
Apply some fixes for integration of code by virgil
Apply same packaging performed on GlobaLeaks software
removed redundant specification of verfy_config_is_sane

dunno why it was in there twice.
Bump to version 3.1.36
Remove outdated scripts
Minor fix avoiding wrong rewrites of pyaloads between two chunks