Add ability to dynamically set url paths
Add ability to dynamically set url paths

This makes GitHub Pages for projects support possible as all urls will need to call on the project's subfolder. The other important piece is that urls should resolve to root locally but be able to change when in production. LLastly this gives themes clear integration points for working with paths. (the jbcache hack just makes it so there is not unnecessary whitespace output in the source.

aadm/aadm.github.io,jershmagersh/p4f.github.com,P4F/p4f.github.com,jhu-chang/jhu-chang.github.io,jhu-chang/jhu-chang.github.io,jhu-chang/jhu-chang.github.io,aadm/aadm.github.io