Added in a extention mapping
Added fake_handler.go, which will serve as a head node in the linked
list, to return a successful handle.
Implemented the linked list structure for handling.
failing without visible errors.
Some adjustments to get shell handlers executing

although black box tests are still borked.  Looking...
A few more tweaks to get us back in the green :smiley_cat:
Merge pull request #28 from modcloth-labs/shell_handler

Shell handler
Merge remote-tracking branch 'origin/master' into switch-to-relative-package-name
Remaining nits.  Onward!