Remove browser checks and use MediaWiki browser policy

We had a browser check to blacklist all browsers older than IE 8
IE <= 7

But that is no longer required since JS support is not there for such
browsers as per https://www.mediawiki.org/wiki/Compatibility#Modern
We can support all modern browsers listed there and we don't need
additional blacklisting now. From 1.27 onwards, there is no JS loaded
for IE 8 too. So we can just use MW browser support policy.

In this commit, the code to do brower checks removed and simplified
the initialization code. Still I am not happy with the interface module,
that need further refactoring.

Change-Id: I655826c55fb2c7c5c88f16368110142d64a96eec

extension.json

@@ -160,7 +160,6 @@
 				"mediawiki.api",
 				"mediawiki.api.options",
 				"mediawiki.cookie",
-				"jquery.client",
 				"jquery.cookie"
 			],
 			"position": "top",
@@ -251,7 +250,8 @@
 			"scripts": "js/ext.uls.webfonts.js",
 			"dependencies": [
 				"ext.uls.init",
-				"ext.uls.preferences"
+				"ext.uls.preferences",
+				"jquery.client"
 			],
 			"localBasePath": "resources",
 			"remoteExtPath": "UniversalLanguageSelector/resources"