Revert "keystore: Fix build with gcc 4.7+ -Werror"

This reverts commit baaaa740b0230cdb78f1641c27d960051bebf822.
Add casts to avoid build warnings with gcc-4.7

Example:
keystore.cpp:1339:35: error: narrowing conversion of 'CommandCodes[0]'
from 'command_code_t {aka unsigned char}' to 'int8_t {aka signed char}'

Change-Id: I8cd239880821724050d1716b78851807e0246ef2
Signed-off-by: Pavel Chupin <pavel.v.chupin@intel.com>
Signed-off-by: Paul Beeler <sparksco@gmail.com>
Switch keystore to binder

Change-Id: I6dacdc43bcc1a56e47655e37e825ee6a205eb56b