Revert "Remove trivial test suite"

This reverts commit a6f0f583cedd9d6ceb4c949fa03b3913620a847c.
Condition minitest
Fix assertions
Add travis config
Remove unused assertion helper
Add gemspec for 1.7.0
Set gemspec path
Depend on rake for dev
Test old rubies
Add json to dev deps
Test coffee-script-source 1.6.3
Test 1.6.0 from travis
Fix gemfile location
Test coffee-script-source 1.6.x
Export generic CoffeeScript::Error
Test coffee-script-source 1.5.0
Test coffee-script-source 1.4.0
Test coffee-script-source 1.3.x
Test coffee-script-source 1.2.0
Test coffee-script-source 1.1.x