Adding Bigtable docs.

[dhermes]

Docs serving (for now at least, as of 12:45pm Pacific on Feb. 26): https://blog.bossylobster.com/gcloud-python/latest/bigtable-usage.html

[dhermes]

@jgeewax PTAL as well

[theacodes]

Does it make sense to stuff the autogen stuff under a ref folder?

[theacodes]

Finished a pass, please let me know when you're ready for another round.

[dhermes]

@jonparrott Just pushed a new commit PTAL. I did a full pass to make sure things still made sense (since the API has changed over time) and found a few changes to make here and there (many are stylistic).

[theacodes]

This LGTM once @jgeewax's comments are addressed.

(Also don't forget to squash)

[dhermes]

Thanks

[dhermes]

Dangling questions to be resolved when #1548 is. Merging now.

[jgeewax]

I see this one is merged -- are the docs up to date on both gh-pages and gcloud-python.readthedocs.org? (http://gcloud-python.readthedocs.org/en/latest/happybase-package.html doesn't look like the demo)

[jgeewax]

/cc @dhermes

[dhermes]

AFK right now but will try to sleuth. Looks like the docs build is broken somehow

[dhermes]

@jgeewax confirmed the build failure: https://readthedocs.org/projects/gcloud-python/builds/3798705/

For example:

/home/docs/checkouts/readthedocs.org/user_builds/gcloud-python/checkouts/latest/docs/happybase-table.rst:4: WARNING: autodoc: failed to import module u'gcloud.bigtable.happybase.table'; the following exception was raised:
Traceback (most recent call last):
  File "/home/docs/checkouts/readthedocs.org/user_builds/gcloud-python/envs/latest/local/lib/python2.7/site-packages/sphinx/ext/autodoc.py", line 385, in import_object
    __import__(self.modname)
  File "/home/docs/checkouts/readthedocs.org/user_builds/gcloud-python/checkouts/latest/gcloud/bigtable/__init__.py", line 18, in <module>
    from gcloud.bigtable.client import Client
  File "/home/docs/checkouts/readthedocs.org/user_builds/gcloud-python/checkouts/latest/gcloud/bigtable/client.py", line 32, in <module>
    from grpc.beta import implementations
ImportError: No module named grpc.beta

I forgot I had a hack in place and will do something similar (but closer to the recommended way of fixing bad imports).