Finit v4.6

Changes

• Add support for service notify:pid and readiness none global
  option to change how Finit expects readiness notification, issue #386

Fixes

• Fix #383: dbus and runparts regression in Finit v4.5. The configure
  script must expand FINIT_RUNPATH_ before defining it in config.h
• Fix #384: service environment variables drop everything but the first
  argument, e.g., VAR="foo bar qux" drops everything but foo
• Fix #385: internal conditions, e.g., <int/bootstrap> turn into flux
  when leaving bootstrap, causing depending services to stop
• Fix #387: global environment variables declared with set VAR=NAME do
  not drop leading set , causing 'set VAR'='NAME' in env.
• Sanity check environment variables, for services and globally. Ensure
  the variable name (key) does not contain spaces, or a leading set