Disabling put encrypt segmented objects and more

Segmented object support needs multiple opens and seeks and isn't
compatible with encryption support.

Made encryption support a set content-length in case it's needed.

Made segmented object support HEADing the segment in case it doesn't
already have the required resulting content-length and etag (really
should never happen, but just in case).

Also fixed a bug with standardclient's put_object call with a set
content-length that can't complete reading.
New encrypt and decrypt cli commands

Useful for local encrypting and decrypting.