Update to Awestruct 0.5.4.rc3

They've been moving things along quickly as it seems there were some
issues in 0.5.3.

  Please enter the commit message for your changes. Lines starting
  with '#' will be ignored, and an empty message aborts the commit.
  On branch fine-tuning
  Changes to be committed:
    (use "git reset HEAD <file>..." to unstage)

 	modified:   Gemfile
 	modified:   Gemfile.lock

  Changes not staged for commit:
    (use "git add <file>..." to update what will be committed)
    (use "git checkout -- <file>..." to discard changes in working directory)

 	modified:   _config/site.yml