add async and defer attributes to piwik.js

inspired from http://piwik.org/docs/javascript-tracking/#toc-where-can-i-find-the-piwik-tracking-code
Fix `utils.copy` behaviour

Previously, the copy util failed if only a directory containing only
files was specified in THEME_STATIC_PATHS
Merge pull request #1075 from jeekajoo/patch-1

Add async and defer attributes to piwik.js
Support for pygment defaults and relevant documentation
Merge pull request #1083 from bmcorser/bmcorser/fix-utils-copy

Fix `utils.copy` behaviour
Merge pull request #1084 from karmadharma/pygmentdocsanddefault

Support Pygments customization in settings (reST only)
Fix a broken link
Merge branch 'master' of github.com:getpelican/pelican
Update changelog
Enhance and correct documentation
Removed obsolete comment.
Support for params and fragments in intrasite links. Adresses #1063.
Change Bumpr test from tox to unittest

There are currently some minor problems when running tox that are not
present when running "python -m unittest discover". Once those problems
have been resolved, we should probably change this setting back to tox.
Modify sed command in bumpr.rc to support BSD

It appears that BSD sed, unlike Linux, has a requirement that you
provide an extension to the -i option. So, while Linux allows:

    sed -i "sed-command"

... to edit in-place, the BSD variant needs to have:

    sed -i "" "sed-command"

i.e., with an empty backup suffix.
Bump version 3.3.0
Prepare version 3.3.1.dev for next development cycle
Watch static folders in Autoreload mode
Attempt to be compilant with Python 3.
Added tests.
Tuned the tests so they are PY3 compilant.