docs(test_plan): add a formal doc describing QA strategy & scope
docs(installing_deis): add quick start guide

This guide adds some quick links to some common tasks that are shared
across multiple cloud provider documentation such as generating a new
SSH key, generating a Discovery URL, configuring DNS and installing
deisctl.
fix(docs): fixup markdown
docs(understanding_deis): refactor architecture, concepts, components
Merge pull request #2448 from mboersma/test-plan-doc

docs(test_plan): add a formal doc describing QA strategy & scope
Merge pull request #2447 from bacongobbler/2446-ssh-key-docs

docs(installing_deis): add quick start guide
Merge pull request #2450 from gabrtv/understanding-deis

docs(understanding_deis): refactor architecture, concepts, components
fix(builder): avoid return an error if is not possible remove an image
docs(customizing_deis): create new section for customization
Merge pull request #2453 from gabrtv/customizing-deis

docs(customizing_deis): create new section for customization
Merge pull request #2452 from aledbf/avoid_builder_push_rm_error

fix(builder): avoid return an error if is not possible remove an image
docs(managing_deis): add store to backup/restore docs
Merge pull request #2415 from carmstrong/backup_restore_store

docs(managing_deis): add store to backup/restore docs
docs(*): doc edits for stable release
Merge pull request #2456 from gabrtv/doc-review

Update documentation in preparation for stable release
docs(readme): update readme in prep for stable
Merge pull request #2458 from gabrtv/update-readme

docs(readme): update readme in prep for stable
docs(README): remove "open an issue for new providers" language
Merge pull request #2459 from mboersma/readme-remove-platform-issues

docs(README): remove "open an issue for new providers" language
docs(*): add Deis resource requirements