Improve travis#4

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larskuhtz wants to merge 7 commits intomasterfrom

Commits on Mar 19, 2015

travis: container based infrastructure
Lars Kuhtz
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Commits on Mar 20, 2015

travis: try out travis caching
Lars Kuhtz
committed
travis: make sure that cache directories exist
Lars Kuhtz
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travis: TEST DO NOT MERGE
Lars Kuhtz
committed
travis: TEST DO NOT MERGE
Lars Kuhtz
committed
travis: TEST DO NOT MERGE
Lars Kuhtz
committed
travis: TEST DO NOT MERGE
Lars Kuhtz
committed