Notify Chaps daemon when login events occur.

When a user performs a login, logout, or change-password their PKCS #11
token needs to respond accordingly. This CL includes the code to fire
these events and the code to derive appropriate authorization data for
the token.

BUG=chromium-os:21003
TEST=Manually test the following cases:
     - Initial login / logout.
     - Subsequent login / logout.
     - Change password and login with full migrate.
     Run the following autotests with chaps enabled / disabled:
     - platform_Pkcs11InitOnLogin
     - platform_Pkcs11InitUnderErrors

Change-Id: I73fae300a39122a5b44ff3fcae200a6504d1208c
Reviewed-on: https://gerrit.chromium.org/gerrit/17658
Tested-by: Darren Krahn <dkrahn@chromium.org>
Commit-Ready: Darren Krahn <dkrahn@chromium.org>
Reviewed-by: Darren Krahn <dkrahn@chromium.org>
6 files changed