test with Ruby 2.2, Rails 4.2 and Prawn 1.3
test unit for Ruby 2.2.0

cannot load such file -- test/unit/assertions (LoadError)
minitest for Ruby 2.2

cannot load such file -- minitest/autorun
Merge pull request #22 from GetJobber/ruby22

test with Ruby 2.2, Rails 4.2 and Prawn 1.3