Fix error detection for invalid command line arguments.

Fix error detection for invalid command line arguments.

This fixes 2 edge cases:
- when an unknown extra parameter is given (it was simply
  ignored before)

  e.g.: "android update sdk foo" => foo is extra.

- when a 1-argument parameter is used and no argument is actually
  given but instead the next dash-parameter is found.

  e.g.: "android update sdk --filter (missing value) --somearg"

Change-Id: Idc34f61728411aceaf1cf33f070ac275b3798019