Implement regular expression support for key searching

There is a use case to use only some part of the full key as a
searching criterion, as an example of such a criterion could be gNBID,
arp or qci. That's why change find_keys() and find_and_get() API
functions to take in a key search pattern instead of a key prefix.
A pattern can contain glob-style regular expression to match a key.

Removed also 'atomic' parameter of find_and_get(), because only
reasonable selection would be to use non-atomic option, which does not
block the whole Redis for a long time as atomic option could do.

Returned dictionary of matched key values are now sorted by key values
in alphabetical order.

Signed-off-by: Timo Tietavainen <timo.tietavainen@nokia.com>
Change-Id: I870089f51b1ce4d72c7984220af0f770b562563f
diff --git a/docs/release-notes.rst b/docs/release-notes.rst
index 92a49a6..e91338d 100644
--- a/docs/release-notes.rst
+++ b/docs/release-notes.rst
@@ -33,6 +33,13 @@
 Version history
 ---------------
 
+[2.0.0] - 2020-01-03
+
+* Change find_keys() and find_and_get() API functions to support glob-style
+  regular expression in a key search pattern. API backward incompatible change.
+* Remove 'atomic' parameter of find_and_get() API function. API backward
+  incompatible change.
+
 [1.0.2] - 2019-12-18
 
 * Take Hiredis package into use in Redis database backend.