add '--project ABCDEF' command line flag

[sygibson]

I'm trying to use the packet tool in a stand-alone environment where I do not want to write a profile out prior to use of the tool. It appears this is required to be able to set the DEFAULT_PROJECT_ID in the profile.

There currently exists the --key KEY option to the arguments, but there is no matching --project flag to set the Project ID. This requires setting the Profile which requires writing out a config file - which is not a desirable trait in my use case.