update travis and gemspec with rake dependency

.travis.yml

@@ -1,3 +1,5 @@
+language: ruby
+
 env:
   - "RAILS_VERSION=3.1"
   - "RAILS_VERSION=3.2"

two_factor_authentication.gemspec

@@ -24,11 +24,12 @@ Gem::Specification.new do |s|
   s.executables   = `git ls-files -- bin/*`.split("\n").map{ |f| File.basename(f) }
   s.require_paths = ["lib"]
 
-  s.add_development_dependency "rspec-rails"
   s.add_runtime_dependency 'rails', '>= 3.1.1'
   s.add_runtime_dependency 'devise'
   s.add_runtime_dependency 'randexp'
   s.add_runtime_dependency 'rotp'
 
+  s.add_development_dependency 'rspec-rails'
   s.add_development_dependency 'bundler'
+  s.add_development_dependency 'rake'
 end