[ldapfeed] move docstring to the class instead of the module

[hook] fix hook base class so access to __registries__ doesn't call check_event, only call it in registered callback. Closes #2517748

[startup hook/looping tasks] separated hook for each looping task to ease modification from cubes. Closes #2517096

[ldaputils] should use entity.eid instead of entity on raising ValidationError. closes #2517095

[dbapi] provide get_option_value over DBAPIRequest (closes #2515522)

Added tag cubicweb-debian-version-3.15.5-1 for changeset 19e115ae5442

Added tag cubicweb-version-3.15.5 for changeset b0e086f451b7

prepare 3.15.5

[entity attr cache] mark attribute as uncacheable in the underlying function else we may miss some changes. Also rewrite a storage test currently failing because cache of the entity created by the test transaction, distinct from the entity created internally and given to hooks and all, has its attributes cache not updated. As this doesn't seems a proper usage, rewrite it as expected. Much probably closes #2423719 definitly.

[repository] move modification of appobject_path to repository initialization code so we can restore it later to avoid side effect on the config. Fix regression introduced in d32ab8570e5d