Improve help strings

Make help strings more consistent:
* Fix spelling and capitalization
* Add "." at end of each string
* Fix spaces.
* Improve wording

Change-Id: I22e84ebecb87f1c803cfb8369db3798fe56903ff
Remove arguments deprecated after Diablo

Change-Id: Ia65ee002ad2aa2b6d2401586d1e06b8ffdb633dd
Closes-Bug: #1279483
Add Python 3 classifiers

Closes-Bug: 1288264
Change-Id: I99c5b19127e66288b5121d6a1399df1b4be0e890
Merge "Add Python 3 classifiers"
Merge "Improve help strings"