Update gradle to 2.11.

Update DMDirc repo to HTTPS.

build.gradle

@@ -30,7 +30,7 @@ subprojects {
 
     repositories {
         mavenCentral()
-        maven { url 'http://artifactory.dmdirc.com/artifactory/repo' }
+        maven { url 'https://artifactory.dmdirc.com/artifactory/repo' }
         maven { url 'https://oss.sonatype.org/content/repositories/snapshots' }
     }
 
@@ -146,7 +146,7 @@ buildscript {
 }
 
 task wrapper(type: Wrapper) {
-    gradleVersion = '2.4'
+    gradleVersion = '2.11'
 }
 
 subprojects.each { evaluationDependsOn it.path }

gradle/wrapper/gradle-wrapper.properties

@@ -1,6 +1,6 @@
-#Fri Jun 12 22:30:53 BST 2015
+#Sun Feb 21 16:59:09 GMT 2016
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-2.4-all.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-2.11-bin.zip