Bundler compatibility
Bundler compatibility

Bundler overwrites Gem::Specification.stubs such that it returns
Gem::Specification instances rather than Gem::StubSpecification
instances.

Fixes #202

mariusbutuc/spring,pigoz/spring,smathy/spring,slobodankovacevic/spring,rails/spring,universsky/spring-1,y-yagi/spring,ypresto/spring,maclover7/spring,grosser/spring