Support for --volume host:container:rw

[prologic]

I'm not sure, but fig doesn't currently seem to support the optional 3rd parameter ro or rw for --volume

[prologic]

$ fig up cadvisor
Creating prologic_cadvisor_1...
Traceback (most recent call last):
  File "/home/prologic/bin/fig", line 9, in <module>
    load_entry_point('fig==0.5.2', 'console_scripts', 'fig')()
  File "/home/prologic/lib/python2.7/site-packages/fig/cli/main.py", line 30, in main
    command.sys_dispatch()
  File "/home/prologic/lib/python2.7/site-packages/fig/cli/docopt_command.py", line 21, in sys_dispatch
    self.dispatch(sys.argv[1:], None)
  File "/home/prologic/lib/python2.7/site-packages/fig/cli/command.py", line 31, in dispatch
    super(Command, self).dispatch(*args, **kwargs)
  File "/home/prologic/lib/python2.7/site-packages/fig/cli/docopt_command.py", line 24, in dispatch
    self.perform_command(*self.parse(argv, global_options))
  File "/home/prologic/lib/python2.7/site-packages/fig/cli/command.py", line 50, in perform_command
    return super(Command, self).perform_command(options, *args, **kwargs)
  File "/home/prologic/lib/python2.7/site-packages/fig/cli/docopt_command.py", line 27, in perform_command
    handler(command_options)
  File "/home/prologic/lib/python2.7/site-packages/fig/cli/main.py", line 340, in up
    recreate=recreate
  File "/home/prologic/lib/python2.7/site-packages/fig/project.py", line 170, in up
    for (_, container) in service.recreate_containers():
  File "/home/prologic/lib/python2.7/site-packages/fig/service.py", line 167, in recreate_containers
    self.start_container(container)
  File "/home/prologic/lib/python2.7/site-packages/fig/service.py", line 233, in start_container
    external_dir, internal_dir = volume.split(':')
ValueError: too many values to unpack

[dnephin]

Duplicate of #260

[prologic]

Confirmed duplicate of #260