Ensure that HHVM defined session.save_path exists

Work around hhvm/packaging#81 by ensuring that any session.save_path
defined in /etc/hhvm/php.ini is created on the local file system. This
change is intended to fix travis-ci/travis-ci#2942.
Use pushd/popd in Firefox plugin

To ensure that the build returns to the correct location at
the end of the addon execution.
Merge pull request #337 from travis-ci/ha-bug-firefox-pwd

Use pushd/popd in Firefox plugin
Merge pull request #327 from bd808/issue/2942

Ensure that HHVM defined session.save_path exists
Add spec for https://github.com/travis-ci/travis-build/pull/327
fix bash echo generator for passing an array of messages
Merge pull request #338 from travis-ci/sf-fix-echo-array

Fix bash echo generator for passing an array of messages
Update url of firefox

http://releases.mozilla.org/pub/firefox/releases has moved http://download.cdn.mozilla.net/pub/firefox/releases permanently
Merge pull request #343 from PeterDaveHello/patch-1

Update url of firefox
Add Google and OpenDNS nameservers

There are reports of DNS lookups failing with some frequency,
and they cause build to fail.
(https://github.com/travis-ci/travis-ci/issues/2965)

This commit aims to address it by adding publicly available and
robust name servers from Google and OpenDNS.
Revert "Update url of firefox"

This reverts commit ad672db00c9fa5fd40f691c7b288dc349ceaebfc.
Spell check variable name
Auto-merged master into ha-feature-dns-fix on deployment.
Merge pull request #344 from travis-ci/ha-feature-dns-fix

Add Google and OpenDNS nameservers
Julia support