update Gradle wrapper and shadow plugin

build.gradle

@@ -4,7 +4,7 @@ buildscript {
     }
     dependencies {
         classpath 'me.champeau.gradle:gradle-javadoc-hotfix-plugin:0.1'
-        classpath 'com.github.jengelman.gradle.plugins:shadow:1.2.2'
+        classpath 'com.github.jengelman.gradle.plugins:shadow:1.2.3'
         classpath 'me.champeau.gradle:japicmp-gradle-plugin:0.1.0'
     }
 }
@@ -72,7 +72,7 @@ subprojects {
 }
 
 task wrapper(type: Wrapper) {
-    gradleVersion = '2.9'
+    gradleVersion = '2.11'
 }
 
 //Task used by Heroku for staging

gradle/wrapper/gradle-wrapper.properties

@@ -1,6 +1,6 @@
-#Mon Dec 14 13:19:40 CET 2015
+#Fri Feb 12 10:36:51 CET 2016
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-2.9-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-2.11-bin.zip

gradlew.bat

@@ -46,7 +46,7 @@ echo location of your Java installation.
 goto fail
 
 :init
-@rem Get command-line arguments, handling Windowz variants
+@rem Get command-line arguments, handling Windows variants
 
 if not "%OS%" == "Windows_NT" goto win9xME_args
 if "%@eval[2+2]" == "4" goto 4NT_args