init v3.3.7
add ref to plugin template
mk exceptions private
mk exceptions private
issue #68
make more robust
don't stop tests on failure
update CHANGES.txt
mk tests more robust
add isbn verification to 'isbntools.meta' (issue #68)
don't overwrite fields with empty values
expose top exceptions
raise exception when the isbn is not valid
verbose tests
pep257
pep257
fix exception message
add logging.debug statements
log request headers
ref top exceptions