fix create_node's {incidents,storage}_dir options

  - logdir -> incidents_dir
  - storedir -> storage_dir
  - removed unnecessary os.path.join
  - removed default "" argument to config.get (there is a None there anyway)
bring back logdir runtime option

  turns out it was actually necessary if you want to run things
more common options for all types of node creation

    allow create-introducer et al to set web.port, incidents_dir and tempdir
expand runtime logdir option to be relative to wd

instead of relative to the basedir
remove unused default argument "" from config.get

this was actually returning None anyway, because these options are actually
present in the dictionary with values of None when they are not specified on
the commandline.
return default introducer web.port to none

No web ui for introducers has been the default behavior for a long time, so
lets leave it that way now even though create-introducer can configure a
web.port now. This also makes the one test that was failing pass.
use tuple instead of list, to match nearby options
Merge pull request #1 from leif/meskio

fix create_node and start_stop_node