Add delete_folder implementation in Python-C gateway and sample backend
pymapistore: modified argument order in default get_root_folder function
pymapistore: fixed typo in initialize()
pymapistore: set the py_MAPIStoreContext_open as METH_NOARGS
pyopenchange: return MAPIStore errors and take talloc and loadparm contexts as arguments in sam_ldb_init
pyopenchange: handle MAPIStore errors on py_MAPIStoreFolder_get_child_count
pymapistore - included convention for return values (retval) in pymapistore.c
pymapistore: use MAPISTORE_RETVAL_IF in sam_ldb_connect
pymapistore: remove the check in py_MAPIStoreFolder_get_child_count - not necessary
pymapistore: py_MAPIStoreFolder_create_folder returns folder object
remove 'syspath' from sam_ldb_init (not used) and move Samba database initialisation from 'new' to 'initialize'