Change spec blocks to use double-quotes

 git reset --hard HEAD; git grep "'" spec | \
   cut -d: -f1 | sort -u | \
    xargs perl -pi -w -e \
    "s/(it|specify|context|describe) '([^']+)' do/\1 QUOTE\2QUOTE do/g;"
 git grep QUOTE spec | cut -d: -f1 | sort -u | \
   xargs perl -pi -w -e 's/QUOTE/"/g;'