handle empty directory and add mocks fixes #195

[beiriannydd]

I know there have been other fixes, but this one includes tests. Sorry for taking so long with the patch, python is about my 4th competency and this is my first time writing tests with this framework.

test run:

SFOLA09DHV2Q:salt fsalwin$ python tests/runtests.py -n unit.grains.test_ec2_info
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 * Python Version: 2.7.10 (default, Feb 7 2017, 00:08:15) [GCC 4.2.1 Compatible Apple LLVM 8.0.0 (clang-800.0.34)]
 * Transplanting configuration files to '/private/tmp/salt-tests-tmpdir/config'
 * Current Directory: /Users/fsalwin/src/salt
 * Test suite is running under PID 96753
 * Logging tests on /private/tmp/salt-runtests.log
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Starting unit.grains.test_ec2_info Tests
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
..
----------------------------------------------------------------------
Ran 2 tests in 0.002s

OK

======================================================================================  Overall Tests Report  ======================================================================================
***  No Problems Found While Running Tests  ********************************************************************************************************************************************************
====================================================================================================================================================================================================
OK (total=2, skipped=0, passed=2, failures=0, errors=0) 
======================================================================================  Overall Tests Report  ======================================================================================