changing import statements back

viper.go

diff --git a/viper.go b/viper.go
index ce86ce3..9eba0cd 100644
--- a/viper.go
+++ b/viper.go
@@ -30,9 +30,9 @@
 	"strings"
 	"time"
 
-	"github.com/jackspirou/cast"
 	"github.com/kr/pretty"
 	"github.com/mitchellh/mapstructure"
+	"github.com/spf13/cast"
 	jww "github.com/spf13/jwalterweatherman"
 	"github.com/spf13/pflag"
 )