[schema] store default attribute values in a Bytes field, allowing python objects as default values
Notes:
* Binary objects grow two methods
* we depend on a newer yams version
* the code is quite simplified as a result of the whole change
* a very old and nasty bug where bool(default values) evaluating to
False not being properly migrated is killed
Closes #2414591.
[MESSAGES CONTROL]
disable-msg = C0301
[VARIABLES]
# Enable / disable this checker
enable-variables = yes
additional-builtins = _, display_name
[BASIC]
required-attributes=
attr-rgx = (w|[a-z_][a-z0-9_]{2,30})
variable-rgx = (w|[a-z_][a-z0-9_]{2,30})$
argument-rgx = (w|[a-z_][a-z0-9_]{2,30})$
[TYPECHECK]
generated-members=debug,info,notice,warning,error,critical,exception