Update gradle to 2.11.

Update DMDirc repo to HTTPS.

build.gradle

@@ -67,7 +67,7 @@ targetCompatibility = 1.8
 
 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' }
 }
 
@@ -77,5 +77,5 @@ apply from: 'gradle/jar.gradle'
 apply from: 'gradle/fatjar.gradle'
 
 task wrapper(type: Wrapper) {
-    gradleVersion = '2.4'
+    gradleVersion = '2.11'
 }

gradle/wrapper/gradle-wrapper.properties

@@ -1,6 +1,6 @@
-#Fri Jun 12 22:27:48 BST 2015
+#Sun Feb 21 16:57:58 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