Also update BUILD.txt

crypto_sha512crypt.c is a clone of nss_sha512crypt.c with the exception that
all usage of NSS and related libraries has been switched to libcrypto.
I renamed nss_sha512crypt.h to sha512crypt.h since it is common to both
crypto_sha512crypt.c and nss_sha512crypt.c. Note that the random number
generator is not seeded manually and thus relies on seeding done
automatically by libcrypto. On some systems without /dev/urandom
seeding may not be performed.
See http://www.openssl.org/docs/crypto/RAND_add.html.
Signed-off-by: George McCollister <georgem@novatech-llc.com>

The code for authentication against a cached password is moved from the
pam responder to a generic sysdb tevent request. The new code can be
used by other components of sssd to verify passwords on their own.

Tests for the sysdb_cache_password and sysdb_cache_auth request are
added and some unneeded or unused code and variables are removed.

Move the upgrade function first and check explicitly for the old ldb name.
Perform upgrades up to v02 first if necessary.
Then proceed as normal letting the normal init functions perform further
upgrades if necessary.
This now works also if there is no "local" provider in the current
configuration.