Revert "Recursively insensitivize the configuration structures"

This reverts commit 8d9577a72e57989b539c3cb7d7691673ed422af1.

The commit is reasonable enough, but this is a major breaking change for Hugo.

We have to figure out how to handle this before we introduce this one.

See https://github.com/spf13/hugo/issues/1129
diff --git a/util.go b/util.go
index 6fef1a4..7c5d21a 100644
--- a/util.go
+++ b/util.go
@@ -17,7 +17,6 @@
 	"io"
 	"os"
 	"path/filepath"
-	"reflect"
 	"runtime"
 	"strings"
 	"unicode"
@@ -36,10 +35,6 @@
 			delete(m, key)
 			m[lower] = val
 		}
-
-		if val != nil && reflect.TypeOf(val).Kind() == reflect.Map {
-			insensitiviseMap(cast.ToStringMap(val))
-		}
 	}
 }
 
diff --git a/viper_test.go b/viper_test.go
index 1039039..76ec0d2 100644
--- a/viper_test.go
+++ b/viper_test.go
@@ -304,7 +304,7 @@
 
 	ks := sort.StringSlice{"title", "newkey", "owner", "name", "beard", "ppu", "batters", "hobbies", "clothing", "age", "hacker", "id", "type", "eyes", "p_id", "p_ppu", "p_batters.batter.type", "p_type", "p_name"}
 	dob, _ := time.Parse(time.RFC3339, "1979-05-27T07:32:00Z")
-	all := map[string]interface{}{"owner": map[string]interface{}{"organization": "MongoDB", "bio": "MongoDB Chief Developer Advocate & Hacker at Large", "dob": dob}, "title": "TOML Example", "ppu": 0.55, "eyes": "brown", "clothing": map[interface{}]interface{}{"trousers": "denim", "jacket": "leather"}, "id": "0001", "batters": map[string]interface{}{"batter": []interface{}{map[string]interface{}{"type": "Regular"}, map[string]interface{}{"type": "Chocolate"}, map[string]interface{}{"type": "Blueberry"}, map[string]interface{}{"type": "Devil's Food"}}}, "hacker": true, "beard": true, "hobbies": []interface{}{"skateboarding", "snowboarding", "go"}, "age": 35, "type": "donut", "newkey": "remote", "name": "Cake", "p_id": "0001", "p_ppu": "0.55", "p_name": "Cake", "p_batters.batter.type": "Regular", "p_type": "donut"}
+	all := map[string]interface{}{"owner": map[string]interface{}{"organization": "MongoDB", "Bio": "MongoDB Chief Developer Advocate & Hacker at Large", "dob": dob}, "title": "TOML Example", "ppu": 0.55, "eyes": "brown", "clothing": map[interface{}]interface{}{"trousers": "denim", "jacket": "leather"}, "id": "0001", "batters": map[string]interface{}{"batter": []interface{}{map[string]interface{}{"type": "Regular"}, map[string]interface{}{"type": "Chocolate"}, map[string]interface{}{"type": "Blueberry"}, map[string]interface{}{"type": "Devil's Food"}}}, "hacker": true, "beard": true, "hobbies": []interface{}{"skateboarding", "snowboarding", "go"}, "age": 35, "type": "donut", "newkey": "remote", "name": "Cake", "p_id": "0001", "p_ppu": "0.55", "p_name": "Cake", "p_batters.batter.type": "Regular", "p_type": "donut"}
 
 	var allkeys sort.StringSlice
 	allkeys = AllKeys()
@@ -512,10 +512,10 @@
 		"age":  35,
 		"owner": map[string]interface{}{
 			"organization": "MongoDB",
-			"bio":          "MongoDB Chief Developer Advocate & Hacker at Large",
+			"Bio":          "MongoDB Chief Developer Advocate & Hacker at Large",
 			"dob":          dob,
 		},
-		"owner.bio": "MongoDB Chief Developer Advocate & Hacker at Large",
+		"owner.Bio": "MongoDB Chief Developer Advocate & Hacker at Large",
 		"type":      "donut",
 		"id":        "0001",
 		"name":      "Cake",