Add support for documentation

[vil1]

We need an uniform process and layout for documentation across the various projects. The sbt-microsite + tut combo feels like the most natural for scala projects.

• add sbt-microsites plugin and provide common configuration (see ... the microsite :-))
• add documentation publication in the release process (depends on Add publication configuration #3)

[mrcmatuszak]

I will take this one.

[softinio]

@mrcmatuszak do you want to add the same here whilst you are at it? Or can I help you with it?

scalaz/scalaz-library.g8#3

[vil1]

@mrcmatuszak did you make any progress on that? Do you need help?