Adding PyPI badges to package READMEs.

[dhermes]

runtimeconfig and speech don't get badges because they aren't on PyPI yet

• @tswast what is the plan for publishing runtimeconfig?
• @daspecster can you add the "add badge to README" to your release checklist for speech?

[dhermes]

To see it in action:

• https://github.com/dhermes/google-cloud-python/tree/add-package-badges/bigquery
• https://github.com/dhermes/google-cloud-python/tree/add-package-badges/bigtable
• https://github.com/dhermes/google-cloud-python/tree/add-package-badges/core
• https://github.com/dhermes/google-cloud-python/tree/add-package-badges/datastore
• https://github.com/dhermes/google-cloud-python/tree/add-package-badges/dns
• https://github.com/dhermes/google-cloud-python/tree/add-package-badges/error_reporting
• https://github.com/dhermes/google-cloud-python/tree/add-package-badges/language
• https://github.com/dhermes/google-cloud-python/tree/add-package-badges/logging
• https://github.com/dhermes/google-cloud-python/tree/add-package-badges/monitoring
• https://github.com/dhermes/google-cloud-python/tree/add-package-badges/pubsub
• https://github.com/dhermes/google-cloud-python/tree/add-package-badges/resource_manager
• https://github.com/dhermes/google-cloud-python/tree/add-package-badges/storage
• https://github.com/dhermes/google-cloud-python/tree/add-package-badges/translate
• https://github.com/dhermes/google-cloud-python/tree/add-package-badges/vision

[tswast]

I didn't have a plan for publishing runtimeconfig. I don't know the process. It's got enough features already that I can start using it once it's published.