[FAB-1411] Pull gradle zip by curl instead of wget

Pull the gradle zip package by using curl instead of wget, so it can
understand the "socks*://" style proxy protocol prefixes, yet support
wget's "http*://" scheme at the same time.

This partially fixes FAB-1411.

Change-Id: I299ae64ea6bc26bf49946a5661c730bfa32166b4
Signed-off-by: Ray Chen <ray@hyperchain.cn>

images/javaenv/Dockerfile.in

@@ -1,5 +1,5 @@
 FROM hyperledger/fabric-baseimage:_BASE_TAG_
-RUN wget https://services.gradle.org/distributions/gradle-2.12-bin.zip -P /tmp --quiet
+RUN curl -sSL https://services.gradle.org/distributions/gradle-2.12-bin.zip > /tmp/gradle-2.12-bin.zip
 RUN unzip -qo /tmp/gradle-2.12-bin.zip -d /opt && rm /tmp/gradle-2.12-bin.zip
 RUN ln -s /opt/gradle-2.12/bin/gradle /usr/bin
 ENV MAVEN_VERSION=3.3.9