* rename hpgit to git-upstream
* rename import-upstream commadn to import
* change all occurrences of hpgit and import-upstream in code,
comments and tests
* code cleanup (remove some typos, improve PEP8 compliance)
* change license from "HP propietary" to "Apache License v2.0"
Change-Id: Ia4f00d662d79ac9725316027a65f4d23ebbd0f02
JIRA:CICD-1319
JIRA:CICD-1318
Davide Guerri