dont assume presence of colour package (fixes #104)
dont assume presence of colour package (fixes #104)

cheungpat/sqlalchemy-utils,marrybird/sqlalchemy-utils,tonyseek/sqlalchemy-utils,JackWink/sqlalchemy-utils,tonyseek/sqlalchemy-utils,rmoorman/sqlalchemy-utils,spoqa/sqlalchemy-utils,konstantinoskostis/sqlalchemy-utils