set up rspec environment

gnucash.gemspec

@@ -18,4 +18,10 @@ Gem::Specification.new do |gem|
   gem.require_paths = ["lib"]
 
   gem.add_dependency "nokogiri"
+
+  gem.add_development_dependency "simplecov"
+  gem.add_development_dependency "rspec"
+  gem.add_development_dependency "rspec-core"
+  gem.add_development_dependency "rspec-expectations"
+  gem.add_development_dependency "rspec-mocks"
 end