Added ErrorMessage.
Added try_get_error_message().
Changed try_get_error_message() to return a string.
Updated log test for string return.
Added add_error_message().
Changed action to use new exception handling.
Added custom create exception function.
Added powl.exception to runtests.sh.
Fixed action.py to use new exception functions.
Added positional parsers.
Changed action key for transaction action.
Renamed main.py to powl.py.
Modified App exception handling to get and print custom error message.
Renamed powl.py to app.py.
Fixed import statement.
Changed QifConverter to use new exception handling.
Changed permissions on test files to be executable.