Java env alpha (#656)

This change adds support for JVM based environment for running Java functions. This is alpha release of JVM environment and might undergo changes.

environments/jvm/Dockerfile

@@ -0,0 +1,10 @@
+FROM maven:3.5-jdk-8 as BUILD
+COPY src /usr/src/myapp/src
+COPY pom.xml /usr/src/myapp
+RUN mvn -f /usr/src/myapp/pom.xml clean package
+
+FROM openjdk:8-jdk-alpine
+VOLUME /tmp
+COPY --from=BUILD /usr/src/myapp/target/env-java-0.0.1-SNAPSHOT.jar /app.jar
+ENTRYPOINT ["java","-Djava.security.egd=file:/dev/./urandom","-jar","/app.jar","--server.port=8888"]
+EXPOSE 8888