v1.8.0

WARNING: This build is broken. Please skip it and move on to https://github.com/rollbar/rollbar-php/releases/tag/v1.8.1 containing a critical fix.

Remove commitizen setup; prefer global usage instead #450
Standardized dev options: enabled, transmit, output, verbose #456
Configurable Exception Raising for rollbar.log #449
Increase memory limits for php5.3 in Travis CI #452
Make the repo commitizen-friendly #447
Amended PR: Add to config minimumLevel option #442
Updated rollbar.js snippet to the latest version (v2.6.1)