These updates allow the after trigger to behave the same as the
original with regards to the execution location of the trigger
within the execution stack.
This adjusts how triggers are implemented during a normal run. Any
defined triggers which are applicable are located and injected into
the run stack as the stack is built, including hook type triggers.
Support is included for dynamic hook lookup.
The data type used when defining triggers has also been relaxed to
support symbols, strings, or constants.
Initial work
commands/up: make sure all names to with_target_vms are strings
providers/docker: create a docker host VM if needed
providers/docker: executor abstraction for driver to eventually support remote
providers/docker: vagrant executor
providers/docker: support creating the machine
providers/docker: status works if host VM is gone
providers/docker: use start fence to get real docker output
core: Call preserves stack ordering
core: support Message post option
providers/docker: Guard some features with HasSSH checks
providers/docker: much better messaging around create/destroy
providers/docker: output the container ID on create
providers/docker: copy the hostmachine Vagrantfile to the data dir
providers/docker: should make host machine before any up action
providers/docker: HandleBox before the host machine
providers/virtualbox: functional_vboxsf to disable vboxsf
providers/virtualbox: synced folder usable method should take 2 args
providers/docker: default machine name to :default