Merge branch 'stoewer' into development
Cache: removed unnecessary try block
Session: add method is_open()
helper: random_str() now uses the base32hex alphabet as default
FChildren: better default value
helper: random_str() now uses the base32hex alphabet as default
helper: random_str() now uses the base32hex alphabet as default
RestStore: better handling of 404 errors in get()
declarative models: remove outdated TODO comments
helper: removed lower case in id_from_location()
convert: some bug fixes
Model: resolve bugs in model definition
NativeDriver: resolved errors in to_model() method
Some bugs fixed
Cache: fixed bug in delete()
UnitTests: old tests adopted to new client api