Replace hard-coded logger names with __name__. For the most part this just uses
the standard conventions to create the same logger hierarchy as existed before.
The only real difference is that loggers created for printing during tests are
no longer part of the 'tuf' hierarchy.
Signed-off-by: Joshua Lock <jlock@vmware.com>
In PR #307, tuf.log is no longer imported by __init__.py. Add an import statement for tuf.log to fix missing handler warning in 'test_init.py. The logger name specified is also incorrect.
