Introducing gemspec:

 - using https for rubygems (security reasons)
 - ignore Gemfile.lock (it is user specific)
 - using gemspec reference in Gemfile
 - prepare for the build-in gem build
Merge branch 'master' into introducing_gemspec
adding rake and fixing deprecation issues:

 - rspec using double instead of mock: https://github.com/rspec/rspec-mocks/issues/153#issuecomment-12208638
 - rspec not_to raise exception with class:  https://github.com/rspec/rspec-expectations/issues/231
Merge branch 'ZsoltFabok-introducing_gemspec'
Merge branch 'master' of github.com:mlainez/leankitkanban
Bump version
Update gemspec