Add Code Climate badge to README
stat_spec: Use `let`.
Fixed problem with rspec and rspec-longrun.
Merge branch 'master' of github.com:SciRuby/nmatrix
Merge branch 'remove-instance-variables-stat-spec' of https://github.com/duggiefresh/nmatrix into duggiefresh_255
Merge pull request #236 from agarie/code_climate_badge

Add Code Climate badge to README
Update history for release
Version bump.