Set default home value (#281)

* Set default home value

* Apply  default home value based on user for run commands

* rename default home function

integration/dockerfiles/Dockerfile_test_run

@@ -21,3 +21,6 @@ RUN rm /etc/baz
 # Test with ARG
 ARG file
 RUN echo "run" > $file
+
+RUN echo "test home" > $HOME/file
+COPY context/foo $HOME/foo

integration/dockerfiles/Dockerfile_test_user_run

@@ -18,4 +18,10 @@ RUN groupadd testgroup
 USER testuser:testgroup
 RUN echo "hey" > /tmp/foo
 USER testuser:1001
-RUN echo "hey2" >> /tmp/foo
+RUN echo "hey2" >> /tmp/foo
+
+RUN useradd -ms /bin/bash newuser
+USER newuser
+RUN echo "hi" > $HOME/file
+COPY context/foo $HOME/foo
+