Sprint 3 injector api and tests

Injector should be up to date and tested. Its limited functionality might still need some testing. Runner had a silly this-that object visibility bug which is now fixed, along with its tests. Runner and injector tests still unfortunately might leave some gearman job servers running, and runner might leave files in the /tmp/ directory. Multiserver client and worker had minor bugs, now fixed. PLEASE see what you can do about the failing multiserver-client disconnect emitting test!