housekeeping
Logger interface
subtle nasty weird make quirk

For my `tidy` task I was using the task’s makefile itself to remember
the last time tidy was run, so that the next time I only tidy the
changed files. Because of this, when any of the direct or indirect
requirements of `tidy` task was missing, or, when running an undefined
task, it was throwing this:

make: *** No rule to make target `SOME_FILE', needed by `build/script-tags.app-libs.html'.  Stop.

This went away as soon as I switched to using a different file for the
last run timestamp.

NOTE: this is a theory I can’t prove, though. 8-|
Get libraries out of the repo

Thanks Bower!