sss_cache did not accept fully quaified domain names.

https://fedorahosted.org/sssd/ticket/1620

The logic that checks if sssd_nss is running and then
sends SIGHUP to monitor or removes the caches was moved
to a function sss_memcache_clear_all() and made public in
tools_util.h.

https://fedorahosted.org/sssd/ticket/1589

Added check for determining, whether database version is higher or
lower than expected. To distinguish it from other errors it uses
following retun values (further used for appropriate error message):
EMEDIUMTYPE for lower version than expected
EUCLEAN for higher version than expected

When SSSD or one of it's tools fails on DB version mismatch, new error
message is showed suggesting how to proceed.

https://fedorahosted.org/sssd/ticket/1584

When working with multiple domains and no
matching objects for deletion were found in the first
domain, the other domains were not searched at all.

Also the ERROR message informing about object not found
(the one printed for each domain) was changed to
DEBUG message.

Removing bad examples of usage of sysdb_transaction_start/commit/end
functions and making it more consistent (all files except of
src/db/sysdb_*.c).

https://fedorahosted.org/sssd/ticket/1336

* Print usage when no options are given
* Report skipped entries
* Print error message when a nonexistent domain is selected

https://fedorahosted.org/sssd/ticket/1301
https://fedorahosted.org/sssd/ticket/1305
https://fedorahosted.org/sssd/ticket/1306