Too much logging to system out when using webapp

**Describe the bug**
The Frank!Runner is now using the Frank!Flow webapp. This generates a lot of logging in the Tomcat window when you go to https://localhost/frank-flow/ I think this is caused by the CXF logging not being configured. I did a small test locally by copying slf4j-api and slf4j-simple jars from ibis-ladybug-test-webapp to frank-runner\build\apache-tomcat-9.0.60\webapps\frank-flow\WEB-INF\lib and adding simplelogger.properties to frank-runner\build\apache-tomcat-9.0.60\webapps\frank-flow\WEB-INF\classes with:

```
org.slf4j.simpleLogger.log.org.apache.cxf.interceptor=WARN
```
This seems to work but maybe we want you use log4j? See https://github.com/ibissource/frank-flow/blob/master/frank-flow-webapp/src/main/resources/log4j2.xml also. I think the name "INVALID CONFIGURATION" needs to be changed or implies that it is work in progress?

**Reporter**
Jaco de Groot

**Category**
Backend

**To Reproduce**
Steps to reproduce the behavior:

1. Start Frank2Example1
2. Goto https://localhost/frank-flow/
3. See logging in Tomcat window

**Expected behavior**
No logging in Tomcat window when using Frank!Flow

**Screenshots**
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**Additional context**
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