Revert "cannot use err (type error) as type string in argument to log.Error"

This reverts commit 0758a840b4a169597e34fe01fde5d13ffb31aa68.

Fixes #88.
diff --git a/.gitignore b/.gitignore
deleted file mode 100644
index 5f46d10..0000000
--- a/.gitignore
+++ /dev/null
@@ -1,27 +0,0 @@
-### Go template
-# Compiled Object files, Static and Dynamic libs (Shared Objects)
-*.o
-*.a
-*.so
-
-# Folders
-_obj
-_test
-
-# Architecture specific extensions/prefixes
-*.[568vq]
-[568vq].out
-
-*.cgo1.go
-*.cgo2.c
-_cgo_defun.c
-_cgo_gotypes.go
-_cgo_export.*
-
-_testmain.go
-
-*.exe
-*.test
-*.prof
-
-# Created by .ignore support plugin (hsz.mobi)
diff --git a/logger.go b/logger.go
index 7e34632..8e4ebab 100644
--- a/logger.go
+++ b/logger.go
@@ -195,9 +195,8 @@
 }
 
 // Error logs a message using ERROR as log level.
-func (l *Logger) Error(args ...interface{}) {
-	s := fmt.Sprint(args...)
-	l.log(ERROR, "%s", s)
+func (l *Logger) Error(format string, args ...interface{}) {
+	l.log(ERROR, format, args...)
 }
 
 // Errorf logs a message using ERROR as log level.