Most of the Travis CI commands are in the '.travis.yml'. The yml format
does not support functions and therefore code duplication is necessary
to run commands across all builds.
To fix this, add a library for common CI functions. Move all Travis CI
code into dedicated scripts and make them call the library first.
Signed-off-by: Lars Schneider <larsxschneider@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>