use standard key format
use standard key format

We now follow the Android standard of providing public key in
PEM format with extension .x509.pem and private key in DER format
with .pk8 extension.

We now default to signing shim with AOSP test key.

Issue: ADEV-280
Depends-Change-Id: I2c63af5b4b1b082f3739157b81bef6ce154c0efa
Change-Id: I378a5d6e33a62808e264bff5e60ba9dd4b9b6a98
Signed-off-by: Andrew Boie <aab045b28152628be6af0e556050d0381fd0a34d@intel.com>

CyanogenMod/android_external_uefi_shim,android-ia/platform_external_uefi_shim,CyanogenMod/android_external_uefi_shim,CyanogenMod/android_external_uefi_shim,android-ia/platform_external_uefi_shim,android-ia/platform_external_uefi_shim