Force to RSpec 2.14 as suite is not compatible with 3.x

Some be_true which should be turned into be_truthy
Some have matchers that were removed, which there is a lib that will provide them
Blow up immediately when something is wrong

Specifically:
  running w/o Bundler will load an incompatible version of RSpec
  running from not-root will mess up all these relative paths
  repositories that don't override inspect can cause suite to hang when printing errors
Fixes broken invoice extension tests
Fixes merge conflict in Gemfile