Production Release

Changes:
HLS Streaming. Major rework of the HLS encoder to increase
multi-threading and hence performance on multi-core processors.
Removed support for generating multi-rate streams via HLS.
Added a '--server-no-deletes' switch to glasscoder(1) to suppress
DELETE transactions (useful when publishing to services such as
Akamai MSL-4 which do not require client-generated publish-point
cleanup).

Credentials Handling. Added '--credentials-file' and '--delete-credentials'
switches to glasscoder(1) while deprecating use of the '--server-auth'
switch. Also added to glasscoder(1) is the ability to use an ssh(1)
identity file (private key) for authentication when publishing HLS streams.
See the glasscoder(1) man page for details.

Bugfixes. See the ChangeLog for details.