Tabs to spaces to be consistent

```
vendor/bin/indent --spaces -r framework/
vendor/bin/indent --tabs -r . --pattern=*.json
vendor/bin/indent --spaces -r . --pattern=*.md
vendor/bin/indent --spaces -r . --pattern=yii.*.js
vendor/bin/indent --spaces -r . --pattern=*.css
```

README.md

@@ -75,11 +75,11 @@ Edit the file `config/db.php` with real data, for example:
 
 ```php
 return [
-	'class' => 'yii\db\Connection',
-	'dsn' => 'mysql:host=localhost;dbname=yii2basic',
-	'username' => 'root',
-	'password' => '1234',
-	'charset' => 'utf8',
+    'class' => 'yii\db\Connection',
+    'dsn' => 'mysql:host=localhost;dbname=yii2basic',
+    'username' => 'root',
+    'password' => '1234',
+    'charset' => 'utf8',
 ];
 ```
 

web/css/site.css

@@ -1,13 +1,13 @@
 html,
 body {
-	height: 100%;
+    height: 100%;
 }
 
 .wrap {
-	min-height: 100%;
-	height: auto;
-	margin: 0 auto -60px;
-	padding: 0 0 60px;
+    min-height: 100%;
+    height: auto;
+    margin: 0 auto -60px;
+    padding: 0 0 60px;
 }
 
 .wrap > .container {
@@ -15,61 +15,61 @@ body {
 }
 
 .footer {
-	height: 60px;
-	background-color: #f5f5f5;
-	border-top: 1px solid #ddd;
-	padding-top: 20px;
+    height: 60px;
+    background-color: #f5f5f5;
+    border-top: 1px solid #ddd;
+    padding-top: 20px;
 }
 
 .jumbotron {
-	text-align: center;
-	background-color: transparent;
+    text-align: center;
+    background-color: transparent;
 }
 
 .jumbotron .btn {
-	font-size: 21px;
-	padding: 14px 24px;
+    font-size: 21px;
+    padding: 14px 24px;
 }
 
 .not-set {
-	color: #c55;
-	font-style: italic;
+    color: #c55;
+    font-style: italic;
 }
 
 /* add sorting icons to gridview sort links */
 a.asc:after, a.desc:after {
-	position: relative;
-	top: 1px;
-	display: inline-block;
-	font-family: 'Glyphicons Halflings';
-	font-style: normal;
-	font-weight: normal;
-	line-height: 1;
-	padding-left: 5px;
+    position: relative;
+    top: 1px;
+    display: inline-block;
+    font-family: 'Glyphicons Halflings';
+    font-style: normal;
+    font-weight: normal;
+    line-height: 1;
+    padding-left: 5px;
 }
 
 a.asc:after {
-	content: /*"\e113"*/ "\e151";
+    content: /*"\e113"*/ "\e151";
 }
 
 a.desc:after {
-	content: /*"\e114"*/ "\e152";
+    content: /*"\e114"*/ "\e152";
 }
 
 .sort-numerical a.asc:after {
-	content: "\e153";
+    content: "\e153";
 }
 
 .sort-numerical a.desc:after {
-	content: "\e154";
+    content: "\e154";
 }
 
 .sort-ordinal a.asc:after {
-	content: "\e155";
+    content: "\e155";
 }
 
 .sort-ordinal a.desc:after {
-	content: "\e156";
+    content: "\e156";
 }
 
 .grid-view th {
@@ -77,15 +77,15 @@ a.desc:after {
 }
 
 .hint-block {
-	display: block;
-	margin-top: 5px;
-	color: #999;
+    display: block;
+    margin-top: 5px;
+    color: #999;
 }
 
 .error-summary {
-	color: #a94442;
-	background: #fdf7f7;
-	border-left: 3px solid #eed3d7;
-	padding: 10px 20px;
-	margin: 0 0 15px 0;
+    color: #a94442;
+    background: #fdf7f7;
+    border-left: 3px solid #eed3d7;
+    padding: 10px 20px;
+    margin: 0 0 15px 0;
 }