Log Message:
Update ruby-rgl to 0.5.3.

2016-05 Release 0.5.3

Horst Duchene
 * Issue #38: Add error handling or dot functions. (719e38, 5a3423)

Thomas Orozco
 * Remove Enumerable Extension (fde8a5)
 * Update to codeclimate-test-reporter 1.x (25fdb5)

Mario Daskalov
 * Clarify that you need graphviz in the README (35a4b4)