Initial error-handling

Launcher now has a span (element/class/etc all totally changeable) for errors to drop into if the server returns any or if there's a problem with making the AJAX request. Works as a nice pattern for any type of flash message. 

Right now it'll get filled with verbatim errors from Node for post file creation and Jekyll build errors. Might be good to delete the newly-created post file if it's causing build failure.

Also fixed an issue where seconds in the date property of YAML front-matter were causing errors.