Update util.js

The change allows for having routes files within subdirectories and eliminating error:
TypeError: undefined is not a function
due to "callback" being undefined
Merge pull request #408 from machinez/master

Update util.js
Added slightly more elaborate heroku instructions
clean up `walk` utils method
change regex for gzipping to gzip all content types that are prefixed with `text`
Merge pull request #419 from TJkrusinski/master

clean up `walk` utils method
Convert tabs to spaces.
Merge pull request #420 from adrianedworthy/tabs-to-spaces

Convert tabs to spaces.
Merge branch 'master' of https://github.com/linnovate/mean