disable http proxy, no more need it

src/main/res/xml/pref_feature.xml

@@ -1,12 +1,6 @@
 <?xml version="1.0" encoding="utf-8"?>
 <PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android">
 
-  <CheckBoxPreference
-      android:defaultValue="false"
-      android:key="isHTTPProxy"
-      android:summary="@string/http_proxy_summary"
-      android:title="@string/http_proxy">
-  </CheckBoxPreference>
   <CheckBoxPreference
       android:defaultValue="true"
       android:key="isDNSProxy"

src/main/scala/com/github/shadowsocks/Shadowsocks.scala

@@ -70,7 +70,7 @@ object Shadowsocks {
 
   val PREFS_NAME = "Shadowsocks"
   val PROXY_PREFS = Array("proxy", "remotePort", "port", "sitekey", "encMethod")
-  val FEATRUE_PREFS = Array("isHTTPProxy", "isDNSProxy", "isGFWList", "isGlobalProxy",
+  val FEATRUE_PREFS = Array("isDNSProxy", "isGFWList", "isGlobalProxy",
     "isBypassApps", "proxyedApps", "isAutoConnect")
   val TAG = "Shadowsocks"
   val REQUEST_CONNECT = 1