cleaning method to take a block instead of start + cleaning
switch from Before/After cucumber hooks to Around with #cleaning
Merge remote-tracking branch 'origin/master' into cleaning
some tests for #cleaning
document DatabaseCleaner.cleaning and usage with around filters in cucumber / rspec / minitest
add check for fiber brokenness where fibers are used
Merge pull request #257 from sherbet/cleaning

DatabaseCleaner.cleaning