Add support of taxonomy 'series'

[gasperphoenix]

Hi, I'm already using the taxonomies categories and tags to organize my posts. The series taxonomy seems to be not supported by the theme. Just adding the section series with values to posts does not generate the respective pages.

Did I do something wrong (e.g. missing parameter in config file)? Or does the theme not yet support series? If not I would vote for adding the feature as this is very useful to structure a blog.

[gasperphoenix]

I just raised pull request #385 for the proposed changes