Remove unecessary target from lalinference/python/Makefile.am

This is a relic from before the Python interpreter wrapper script.
Strip usage string of leading and trailing whitespace

It is a common enough to have docstrings that look like this:

"""
Documentation for this script
"""

We don't need the extra leading and trailing newlines in the --help
output.
Move docstrings before future statements

Docstings are allowed before future statements. Conversely, strings are
not recognized as docstrings if they come after future statements.