Deis: Various documentation fixes.
Appfrog: Various documentation fixes.
Update Homebrew `brew upgrade` command suggestions

The previous command would still fail if the command wasn't outdated, since both sides of an && would need to pass for the command as a whole to pass.

See travis-ci/travis-ci#2641.
typo in cocoapods caching docs
Update Perl versions.

Fixes https://github.com/travis-ci/travis-ci/issues/2649
Merge pull request #101 from orta/patch-1

typo in cocoapods caching docs
Add error messages when Homebrew errors
Merge branch 'gh-pages' of github.com:travis-ci/docs-travis-ci-com into gh-pages
only sshkey is not available on org
Add section paralellizing your build on multiple VMs
Add example to parallelizing on multiple VMs section
add TravisPy
add Python to apps ToC
add Tron CI to apps
Update Firefox version
Merge branch 'gh-pages' of github.com:travis-ci/docs-travis-ci-com into gh-pages
Announce suspension of multi-OS feature
Better header for parallelizing on multiple VMs. Text fixes.
Merge pull request #104 from travis-ci/ha-suspending-mutlit-os-feature

Announce suspension of multi-OS feature
Merge pull request #103 from ArturT/parallelizing-on-multiple-vms

Add section paralellizing your build on multiple VMs