Merge pull request #31 from eswierk/master

Various changes
minimize use of "from module import *"

This statement was causing strange bugs because of namespace pollution. The
order of imports mattered because later "from module import *" statements would
overwrite modules imported earlier. Transitive imports also made it difficult
to figure out where an identifier was being imported.

This statement is still allowed in test code since nothing else should be
importing it.
add eth platform and --interfaces command line option

When using the eth platform you can give oft multiple "-i ofport@interface"
options to specify which ethernet interfaces to use for the dataplane, instead
of needing to write your own platform file.
change default platform to "eth"

If no --interface options are passed the config is the same as the old local
platform.
oft: remove log when adding test
parse: remove uses of from module import *

Since there is now both an action class named "vendor" and a message class
named "vendor" they clash when imported into the same namespace.
Remove obsolete files