Reimplement old Commands unit tests in order to insure behavior
Merge pull request #1277 from dotcloud/add_commands_unit_tests

* Tests: Reimplement old Commands unit tests in order to insure behavior
Copy authConfigs on save so data is not modified

SaveConfig sets the Username and Password to an empty string
on save.  A copy of the authConfigs need to be made so that the
in memory data is not modified.
Add regression test for authConfig overwrite
Merge pull request #1283 from crosbymichael/username-not-set

Copy authConfigs on save so data is not modified