Change script usage examples
Add execution of script usage tests in all_tests

A test data directory has been added to the repository containing sample
data to run script usage tests.

all_tests.py has been update to by default execute all of the script
usage tests in the scripts directory. Some changes that happened in this
script:
    - Variable name clean-ups
    - Option name changes
    - Addition of options to specify a scripts dir as well as a test
      data dir, both of these are optional, if not provided the script
      will try to automatically find these.

This fixes #44
Change script interface to not take test_data_dir

There is no need to take this path since it exists in the tests
directory and the script will only exist in the tests directory.
Merge pull request #51 from ElDeveloper/issue_44

Add test data to emperor -- fixes issue 44