Remove .DS_Store files

These .DS_Store files do not belong in the directory.

Change-Id: I7ab580d1e61d282051b9d3c3c4a84d5debf4c9d0
Enhance .gitignore

Add generated file image-api-v2.0.xml.
Add common editor backup files.

Change-Id: If3e5702250a02348cca6a1ca8d136e4ffc9d9c08
Merge "Enhance .gitignore"
Setup for openstack-doc-tools

Setup repository so that we can gate using the openstack-doc-tools
tools. Update documentation with details.

Change-Id: Ib88e23562e153afbea2d5a0f30f085adb969f604