allow more granular setup of project folders

[kaizau]

Enjoying Frank so far! One quip:

The current setup options limit one's ability to structure projects as wanted (assumes static, dynamic, layouts groupings). Would love to have more granular control:

Frank.haml_folder = "source"
Frank.layouts_folder= "source/layouts"
Frank.sass_folder = "source/scss"
Frank.images_folder = "source/img"
Frank.export_css_folder = "public/css"
# etc

Currently, simply nesting layout_folder within dynamic_folder seems to break Tilt.

[trvsdnn]

The next release is going to merge static/dynamic. I'm not sure where layouts will go yet, but that may solve some of this issue.