Display system_info output if it exists
Change anticipated text file location

After looking at http://www.wikiwand.com/en/Filesystem_Hierarchy_Standard
and some discussion about Homebrew unlikely to be happy with
`/usr/local` being used, we settle with
`/usr/share/travis/sytem_info` as a better location going forward.
do not assert bundle clean
Merge pull request #331 from travis-ci/sf-dont-assert-bundle-clean

Do not assert bundle clean
reduce the number of git folds
make Git a higher level class, strategies Tarball, Clone, SshKey
split up git specs
use higher level builder dsl methods in firefox, extract install_dir, source_url and such
split out Chruby from RVM
split RVM#setup_rvm method
bring back artifacts refactoring
fold the git tarball strategy
git ssh_key: keep msgs, use sh.newline for adding line padding, add specs
git tarball: rename oauth_token to auth_header, and simplify
add a header stage, add a spec for travis_artifacts_install being run
change the method order to match the flow better
system_info: fix the file name, add outputting the build script language
add an extra newline after the system_info fold
system_info: output dist and group if given
system_info: only output attrs that have a value