Add SimpleCov coverage when running tests under 1.9 (though it doesn't seem to measure correctly...?).

process_shared.gemspec

@@ -17,4 +17,5 @@ Gem::Specification.new do |s|
   s.add_development_dependency('rake-compiler')
   s.add_development_dependency('minitest')
   s.add_development_dependency('minitest-matchers')
+  s.add_development_dependency('simplecov')
 end