Use C99 initialisers for cipher_aliases. This improves readability,
removes the need for zero values to be specified (meaning that we usually
specify two fields instead of 12), makes the field names grepable and
protects from future field reordering/removal.

ok beck@ miod@
Clean up the tls1_change_cipher_state() key length handling and use a
single variable with a descriptive name, instead of two poorly named
variables.

Largely based on Adam Langley's chromium patches.

ok miod@