Created documentation for Intl extension
merged branch naitsirch/master (PR #87)

This PR was squashed before being merged into the master branch (closes #87).

Discussion
----------

Created documentation for Intl extension

Created documentation for Intl extension. It would be nice if this could be integrated. Otherwise it's hard to find the `localizeddate` filter and the needed arguments.

Thanks for this extension ;-)

Commits
-------

138403a Created documentation for Intl extension
modernized the way unit tests are handled
fixed tests for PHP 5.4
fixed markup
switched from camelCase to underscore for intl arguments in the documentation
fixed makrup
fixed markup
sync with upstream and resolve conflicts