Revert "Revert to an older version of kerl"
Revert "Revert to an older version of kerl"

This reverts commit 783c8dc346032ee37502ceab73771d6858bcbe1c.

The issue was not with kerl but with the fact that we do not clean up
build artifacts and eventually run out of disk space on the / partition.

0xCCD/travis-cookbooks,Zarthus/travis-cookbooks,ardock/travis-cookbooks,gavioto/travis-cookbooks,Zarthus/travis-cookbooks,dracos/travis-cookbooks,ljharb/travis-cookbooks,DanielG/travis-cookbooks,ardock/travis-cookbooks,Acidburn0zzz/travis-cookbooks,dracos/travis-cookbooks,bd808/travis-cookbooks,0xCCD/travis-cookbooks,travis-ci/travis-cookbooks,Acidburn0zzz/travis-cookbooks,travis-ci/travis-cookbooks,vinaykaradia/travis-cookbook-cloned,Zarthus/travis-cookbooks,vinaykaradia/travis-cookbook-cloned,ljharb/travis-cookbooks,alex/travis-cookbooks,ljharb/travis-cookbooks,alex/travis-cookbooks,DanielG/travis-cookbooks,Distelli/travis-cookbooks,johanneswuerbach/travis-cookbooks,travis-ci/travis-cookbooks,bd808/travis-cookbooks,tianon/travis-cookbooks,ardock/travis-cookbooks,tianon/travis-cookbooks,gavioto/travis-cookbooks,dracos/travis-cookbooks,spurti-chopra/travis-cookbooks,vinaykaradia/travis-cookbook-cloned,spurti-chopra/travis-cookbooks,DanielG/travis-cookbooks,vinaykaradia/travis-cookbook-cloned,tianon/travis-cookbooks,tianon/travis-cookbooks,vinaykaradia/travis-cookbook-cloned,gavioto/travis-cookbooks,dstufft/travis-cookbooks,spurti-chopra/travis-cookbooks,tianon/travis-cookbooks,DanielG/travis-cookbooks,johanneswuerbach/travis-cookbooks,Acidburn0zzz/travis-cookbooks,dstufft/travis-cookbooks,bd808/travis-cookbooks,johanneswuerbach/travis-cookbooks,Distelli/travis-cookbooks,Zarthus/travis-cookbooks,dracos/travis-cookbooks,Distelli/travis-cookbooks,Distelli/travis-cookbooks,ardock/travis-cookbooks,Acidburn0zzz/travis-cookbooks,gavioto/travis-cookbooks