Issue 110: Remove spurious COPY command that is sometimes causing pro…

…blems.

Update the SOURCE_DIR as it doesn't need the leading slash.

The copy over build artifact in the maven stage is not used.
Remove it.

Dockerfile

@@ -2,7 +2,7 @@
 ARG USER_ID=3001
 ARG USER_NAME=iriifservice
 ARG HOME_DIR=/$USER_NAME
-ARG SOURCE_DIR=/$HOME_DIR/source
+ARG SOURCE_DIR=$HOME_DIR/source
 
 # Maven stage.
 FROM maven:3-openjdk-11-slim as maven
@@ -36,9 +36,6 @@ USER $USER_NAME
 # Build.
 RUN ["mvn", "package", "-Pjar", "-DskipTests=true"]
 
-# Copy over the built artifact.
-COPY ./target/ROOT.jar $HOME_DIR/iriif.jar
-
 # Switch to Normal JRE Stage.
 FROM openjdk:11-jre-slim
 ARG USER_ID