plieser-EtE_encryption/tests: added write test for encrypted file
plieser-EtE_encryption/client: fixed bugs in object_encryptor and hash_tree_ad
plieser-EtE_encryption/tests: updated write test for encrypted file
plieser-EtE_encryption/client: fixed bug in object_encryptor and hash_tree_ad for write behind current file size
plieser-EtE_encryption/client: added call to truncate and fixed bugs in object_encryptor
plieser-EtE_encryption/tests: added truncate test for encrypted file
plieser-EtE_encryption/client: fixed bugs in object_encryptor and hash_tree_ad