enable caching for pull requests
Godep integration behavior updates per feedback from @kr on #309
Merge pull request #305 from travis-ci/rkh-cache-prs

enable caching for pull requests
Change firefox download location

releases.mozilla.org is CDN'd, while ftp.mozilla.org is not.
This should result in much faster downloads when the pre-installed
firefox is not sufficient.
Fix spec to match the previous commit
Merge pull request #312 from travis-ci/db-godep-tweaks

Godep integration behavior updates per feedback from @kr on #309
Exporting NVM_NODEJS_ORG_MIRROR to work around nodejs.org switch to https
Merge pull request #313 from travis-ci/db-bugfix-nvm-workaround

Exporting NVM_NODEJS_ORG_MIRROR to work around nodejs.org switch to https
Re-sourcing nvm.sh
Getting more heavy handed with nvm
Merge pull request #314 from travis-ci/db-bugfix-nvm-workaround

[WIP] More nvm workarounding
Backing out nvm workaround
Announcing nvm version for node_js builds
Merge pull request #315 from travis-ci/db-nvm-rollback

Backing out nvm workaround
Merge pull request #316 from travis-ci/db-announce-nvm-version

Announcing nvm version for node_js builds
Merge branch 'master' into ha-bug-gh-2820