Update setup.py and conf.py for 0.2.0 (tf-encrypted#251)

Bump for 0.2.0-rc2 (tf-encrypted#249)

Release Branch for 0.2.0-rc0 (tf-encrypted#246)

* Release Branch for 0.2.0-rc0

* Bump to 0.2.0-rc1

Fix CircleCI Tag Filtering (tf-encrypted#245)

When we switched to a PEP440 compliant tag format we forgot to update
our Circle CI configuration to look for tags following that format.

Update setup.py for 0.1.0 (tf-encrypted#127)

Update setup.py for 0.1.0-rc0 release (tf-encrypted#125)