Add missing package subprocess.api.

Missing package caused import error on fresh installs.

- Add test confirming import error.
- Add missing package.
Add missing cp command.
Merge pull request #5 from modocache/improve-tutorial

Add missing package subprocess.api.
removes document html from repository
updates tutorial
wip: updates log analysis example
bugfix: I found `worker_select_queue_local_first_and_random` does not work on some occasion.
If ascendant job has multiple job instances, descendant job instances must pop batches from all of the ascendant workers.
But non-randomized storategy can ignore some of ascendant workers, it leads to stray (not-popped) batches.

Signed-off-by: Sho Nakatani <lay.sakura@gmail.com>
Merge branch 'apache_log_analysis_debug' into dev
follows queue pop api changes
Merge branch 'dev' of github.com:laysakura/shellstreaming into dev
Merge branch 'dev'