Merge branch 'pw/p4-docs-and-tests'

* pw/p4-docs-and-tests:
  git-p4: document and test submit options
  git-p4: test and document --use-client-spec
  git-p4: test --keep-path
  git-p4: test --max-changes
  git-p4: document and test --import-local
  git-p4: honor --changesfile option and test
  git-p4: document and test clone --branch
  git-p4: test cloning with two dirs, clarify doc
  git-p4: clone does not use --git-dir
  git-p4: introduce asciidoc documentation
  rename git-p4 tests