update CHANGELOG.md with 1.5.0 and 1.6.0 version contents

Merge pull request sirupsen#1108 from cirelli94/fix-wrong-caller

Fix wrong caller

Release 1.4.2

Release 1.4.1

Merge pull request sirupsen#920 from sirupsen/changelog-v140

Add CHANGELOG for v1.4.0

Merge pull request sirupsen#863 from lugray/generic_log

Add Generic Log functions with level via argument

v1.2.0

This new release introduces:
  * A new method SetReportCaller in the Logger to enable the file, line and calling function from which the trace has been issued
  * A new trace level named Trace whose level is below Debug
  * A configurable exit function to be called upon a Fatal trace
  * The Level object now implements encoding.TextUnmarshaler interface

Update changelog for v1.1.1 release

Update changelog for v1.1.0 release

Merge branch 'moriyoshi/refix-707' of git://github.com/moriyoshi/logr…

…us into fix_firehooks