refactor: update the Dockerfile image base

Use the image which allows no source file

Author: Sylvain Fraïssé

Dockerfile

@@ -1,4 +1,4 @@
-FROM techio/maven3-builder:1.3
+FROM techio/maven3-builder:1.4
 
 ENV TECHIO_RUN_DIR /project/answer
 

README.md

@@ -2,14 +2,14 @@
 
 First, this runner compiles the project and generate all jars (project + dependencies).
 
-At each play, it compiles user's answer using `javac` and run the specified testcase using junit4. 
+At each play, it compiles user's answer using `javac` and run the specified testcase using junit4.
 
 
 # How to Use
 
 To use this runner for your project, edit the `codingame.yml` file and add the following lines to your project:
 
-    runner: techio/java-maven3-junit4-runner:1.1.3-java-8
+    runner: techio/java-maven3-junit4-runner:1.1.4-java-8
 
 ## Example