Removed unused bower.json files. Adjusted version dependencies.

bower.json

-{
-    "name": "yii2-bootstrap",
-    "version": "2.0.0",
-    "homepage": "http://www.yiiframework.com/",
-    "authors": [
-        "Qiang Xue <qiang.xue@gmail.com>"
-    ],
-    "description": "The Twitter Bootstrap extension for the Yii framework",
-    "keywords": [
-        "yii2",
-        "bootstrap"
-    ],
-    "license": "BSD-3-Clause",
-    "ignore": [
-        "/*"
-    ],
-    "dependencies": {
-        "bootstrap": ">=3.0.0"
-    }
-}

composer.json

@@ -19,7 +19,7 @@
     ],
     "require": {
         "yiisoft/yii2": "*",
-        "bower-asset/bootstrap": "3.2.*"
+        "bower-asset/bootstrap": "~3.2"
     },
     "autoload": {
         "psr-4": {