Fix migrate and create-migration FileNotFound Err

Updated create_migration.clj and migrate.clj to work correctly with lein
2. Fixes #16.
arg parser
add a parser to the arg specs
specify a config function from the command line, let the config init function modify the migration config
throw an exception if config function can't be found
Merge pull request #22 from mccraigmccraig/dynamic-config

Dynamic config
Merged in the ghostandthemachine pull request.
Added the ability to listen to migration events.
Added a test for adding and removing listeners to the runner.
Switched the runner listener call to use Boolean instead of the primative to ensure they type hints work.
Added a test for large numbers of migrations.
Updated the version to 1.4.6
Updated the version to 1.4.7-SNAPSHOT
Added the migration count function.
Updated the version to 1.5.0
Updated the version to 1.5.1-SNAPSHOT