Merge pull request #52 from cemerick/master

Fix default-argument defspec macro usage
Remove trailing whitespace
Release 0.5.4
Prepare for 0.5.5
Release 0.5.5

0.5.4 was pushed to Clojars.org with the wrong code. Not sure how this
happend. The 0.5.4 git _tag_ is correct.
Prepare for 0.5.6
ensure that rand-range yields values inclusive of both lower & upper bounds, fixes gh-54