Fix `ImportError: cannot import name Args`

Traceback (most recent call last):
  File "…/usr/bin/legit", line 4, in <module>
    import legit.cli
  File "…/lib/legit/legit/cli.py", line 16, in <module>
    from clint import Args

Ref: https://github.com/kennethreitz/legit/pull/130
Ref: https://github.com/kennethreitz/legit/pull/131