Optimize build task

It now works with a build and a dist folder. The build folder isn't
deleted after building dist. The build folder contains the entire site,
but isn't optimized or compressed. This'll be useful for development.

The dist folder will contain the entire site as well, but completely
optimized. One thing that still has to be figured out is the relative
paths for scripts, css, etc.
Add develop task, closes #8

Develop task builds to the build folder, opens index.html, watches
and rebuilds on changes. Basic task structure is done. An optional
deploy task could still be added.
Merge branch 'taskstructure' into develop