Issue #769: Add drainpipe-dev ignore folder. (#840)

* Issue #769: Add drainpipe-dev ignore folder.

* Issue #769: Add drainpipe-dev exclude composer.

* Issue #769: Update drainpipeignore file.

* Issue #769: Update drainpipeignore and gitignore files.

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Co-authored-by: David Burns <david@lullabot.com>

Author: Drainpipe