gradle: bump version in wrapper to 3.1

Also re-run `gradle wrapper` from 3.1 to update the scripts and jar.

gradle/wrapper/gradle-wrapper.properties

@@ -2,5 +2,5 @@ distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-2.14.1-bin.zip
-distributionSha256Sum=cfc61eda71f2d12a572822644ce13d2919407595c2aec3e3566d2aab6f97ef39
+distributionUrl=https\://services.gradle.org/distributions/gradle-3.1-bin.zip
+distributionSha256Sum=c7de3442432253525902f7e8d7eac8b5fd6ce1623f96d76916af6d0e383010fc

gradlew

@@ -161,4 +161,9 @@ function splitJvmOpts() {
 eval splitJvmOpts $DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS
 JVM_OPTS[${#JVM_OPTS[*]}]="-Dorg.gradle.appname=$APP_BASE_NAME"
 
+# by default we should be in the correct project dir, but when run from Finder on Mac, the cwd is wrong
+if [[ "$(uname)" == "Darwin" ]] && [[ "$HOME" == "$PWD" ]]; then
+  cd "$(dirname "$0")"
+fi
+
 exec "$JAVACMD" "${JVM_OPTS[@]}" -classpath "$CLASSPATH" org.gradle.wrapper.GradleWrapperMain "$@"

gradlew.bat

@@ -49,7 +49,6 @@ goto fail
 @rem Get command-line arguments, handling Windows variants
 
 if not "%OS%" == "Windows_NT" goto win9xME_args
-if "%@eval[2+2]" == "4" goto 4NT_args
 
 :win9xME_args
 @rem Slurp the command line arguments.
@@ -60,11 +59,6 @@ set _SKIP=2
 if "x%~1" == "x" goto execute
 
 set CMD_LINE_ARGS=%*
-goto execute
-
-:4NT_args
-@rem Get arguments from the 4NT Shell from JP Software
-set CMD_LINE_ARGS=%$
 
 :execute
 @rem Setup the command line