moved gems to groups
added coveralls
added coveralls to readme
Merge branch 'feature/coveralls' into develop

* feature/coveralls:
  added coveralls to readme
  added coveralls
  moved gems to groups
removed Gemfile.lock from stage
fixed line numbers in test
fixed line number in accrue! method
Merge branch 'bugfix/coverage' into develop

* bugfix/coverage:
  fixed line number in accrue! method
  fixed line numbers in test
bump version to 0.5.1
Merge branch 'develop'

* develop:
  bump version to 0.5.1
  fixed line number in accrue! method
  fixed line numbers in test
  removed Gemfile.lock from stage
  added coveralls to readme
  added coveralls
  moved gems to groups