Adds configurable plugin support Fixes #12

[jamelt]

Added simple way to add configurable plugin support to hexo-renderer stylus. You just add the name of the module and it will apply it.

[coveralls]

Coverage remained the same at 100.0% when pulling d44103d on jamelt:master into ed52102 on hexojs:master.

[coveralls]

Coverage remained the same at 100.0% when pulling d44103d on jamelt:master into ed52102 on hexojs:master.

[coveralls]

Coverage remained the same at 100.0% when pulling d44103d on jamelt:master into ed52102 on hexojs:master.

[curbengh]

Looks interesting, can you rebase and refactor to ES6?

[jamelt]

No, this stuff predated any ES6 in this repo. Feel free to make the updates or reject the pull request.

[curbengh]

Superseded by #38