[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.

\.svn
^build$
^dist$
\.pyc$
\.pyo$
\.bak$
\.old$
\~$
\#.*?\#$
\.swp$
^doc/book/en/apidoc$
\.old$
syntax: regexp
.*/data/database/.*\.sqlite
.*/data/database/.*\.config
.*/data/database/tmpdb.*
.*/data/ldapdb/.*
^doc/html/
^doc/doctrees/
^doc/book/en/devweb/js_api/