Fixed command line encoding

[nielsdraaisma]

I tried running the example invocation
jwt --key=secret iss=me exp=1302049071

This failed and returned an error "Not enough segments" followed by a sys.exit(1).
It looks like it tried to parse the encoding parameters and JWT token data, which obviously fails.

I've worked around it and the example scenario's work,but may be a --encode/--decode parameter would be more explicit.

[jpadilla]

Ugh this thing. I think it either needs to go or get rebuilt. Plus it needs some kind of tests.

@nielsdraaisma do you use it for anything significant/important?

[nielsdraaisma]

Don't use it at all, came across it looking for something that could generate a token, and that was broken.

[mark-adams]

@jpadilla Are we wanting to keep this? Is it useful?

[jpadilla]

@mark-adams blah I'd be happier without it really. What would the best "semver" way of getting rid of it soon?