Prepare release 1.2.0

Author: Yuri Shkuro

CHANGELOG.md

@@ -1,6 +1,23 @@
 Changes by Version
 ==================
 
+
+1.2.0 (2020-07-01)
+-------------------
+
+* Restore the ability to reset the current span in context to nil (#231) -- Yuri Shkuro
+* Use error.object per OpenTracing Semantic Conventions (#179) -- Rahman Syed
+* Convert nil pointer log field value to string "nil" (#230) -- Cyril Tovena
+* Add Go module support (#215) -- Zaba505
+* Make SetTag helper types in ext public (#229) -- Blake Edwards
+* Add log/fields helpers for keys from specification (#226) -- Dmitry Monakhov
+* Improve noop impementation (#223) -- chanxuehong
+* Add an extension to Tracer interface for custom go context creation (#220) -- Krzesimir Nowak
+* Fix typo in comments (#222) -- meteorlxy
+* Improve documentation for log.Object() to emphasize the requirement to pass immutable arguments (#219) -- 疯狂的小企鹅
+* [mock] Return ErrInvalidSpanContext if span context is not MockSpanContext (#216) -- Milad Irannejad
+
+
 1.1.0 (2019-03-23)
 -------------------