simplify locales

Author:    Claudio Canepa <ccanepacc@gmail.com>
updatet .travis.yml to support two locales - eliminated abreviations in imports
compat 2.x in locale linux codepath
test_rss_feeds initializes LocaleBorg in setUp
LocaleBorg services as instance methods to ensure initialization
reshaping paranoid damage control forcalendar in windows
allow configure which locales in testing with environmet variables NIKOLA_LOCALE_DEFAULT and NIKOLA_LOCALE_OTHER
update changelog
Include XML in sitemap.

Filter out known unwanted files (such as the sitemap itself).

Resolves issue #804.
addresed kw review
fixed remaining _linux -> _posix
refactored post compilation into the Post object
Fix tests
Fix tests
Include XML in GZIP_EXTENSIONS (for RSS, sitemap)

Resolves #844
Add a note about rebasing to CONTRIBUTING.rst
Merge pull request #845 from getnikola/config-compress-xml

Include XML in GZIP_EXTENSIONS (for RSS, sitemap)
add .xml to default config (via 87b0bde)

Thanks @punchagan
Tests XML for root element rss instead of blacklisting paths
Merge branch 'master' of https://github.com/getnikola/nikola into include-rss-in-sitemap

Conflicts:
	CHANGES.txt
	nikola/plugins/task/sitemap/__init__.py