adds code coverage tool simplecov

updates Gemfile and Gemfile.lock
adds loading of simplecov at the very top of spec helper

adds .simplecov file for centralized config
adds launching of simplecov to .simplecov
updates bin/rails and bin/rake

bundle did update this while installing simplecov with 'bundle'-command
updates bin/rails and bin/rake

bundle did update this while installing simplecov with 'bundle'-command

fixes #41
Merge branch 'add-simple-cov' of https://github.com/Imnudar/gemoria into add-simple-cov
Merge branch 'Imnudar-add-simple-cov'