Updated from global requirements

Change-Id: I09331634dc4fbc0d7bb9030eea6bb36e4db5f8e7
Follow style guide for help strings

Improve help strings to follow the style guide:
* Capitalize first word of each help string
* Finish help strings with "."
* Improve wording and follow usual capitalization

Change-Id: Iecab34edd35175dcf1cccd4676e5cd91752549ad
Do substitution on overrides and defaults too

Some of our consuming projects are setting defaults or overrides
on config objects that look like $state_path/some/file and we're
no longer handling that correctly since commit
2422d4118c97734067ea0b37ae159bc2e3c492c5

Change-Id: I4324bda6f3de3cdf05f8eb3cf16052c04018dec8
Closes-Bug: #1282250
Merge "Follow style guide for help strings"
Merge "Do substitution on overrides and defaults too"
Include the 'meta' trove classifiers for python versions

Change-Id: I76caa576d9490dfbc9f405d4fb1e9ec0ded762af