init v3.3.7
which cache to use is now dinamic
which cache to use is now dinamic
expose IMCache
add isbn verification to 'isbnlib.meta' (close #2)
don't overwrite fields with empty values
expose main exception in dev (close #1)
move isbn validation from 'meta' to '_metadata.query'
raise exception when isbn is not valid
verbose tests
fix exception message
add logging.debug statements and fix UA string
log request headers
update CHANGES.txt
update version
update tox.ini
ref to top exceptions
clarify exceptions use
fmt
fmt