Move test logs to tmp/integration-test-logs

Signed-off-by: Maria Shaldibina <mshaldibina@pivotal.io>
Overwrite test tmpdir to use logs directory

if tmpdir is not on the same device (as on gocd) package installation
fails with invalid cross-device link
Set test agent tmp dir in base dir
clean bundler env before calling out to bosh-registry
[traveling-bosh] loosen constraints so don't need to rebase as much
permit newer nokogiri
allow upstream vcloud_cpi improvements that include nokogiri updates
update thin & dependencies to latest; ready for traveling-ruby native gems
ensure access to latest fixed vcloud cpi
merge clean-bundler/loosen-constraints branch