Allow installation of pdepend for SF and "Other PHP" projects

[rjkip]

As originally submitted by @DRvanR

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see https://pdepend.org/documentation/getting-started.html

Also: https://pdepend.org/documentation/handbook/index.html

Simple way to get the reporting to the repo: https://github.com/travis-ci/dpl#github-pages

• save the output summary.xml and images in a specific directory
• push the images to a (e.g.) qa-tools-phpmd-reports branch

Also consult https://docs.travis-ci.com/user/deployment/#Uploading-Files (and following sections) on how to configure the deploy tool