validate-module returns exit code 1 on successful validation

[pandabear]

Description:

I tried using master-branch built dbptk to validate a siard file on linux environment.

I noticed upon trying siard file validation out that it always returns exit code 1 regardless whether it was invoked to validate a valid or invalid siard file. On shell environment, exit code 1 usually implies that an error has happened while exit code 0 means there is no error.

Steps required to reproduce the bug:

1. Execute java -jar dbptk-app-2.11.0-SNAPSHOT.jar validate.
2. Execute echo $?, see how it returns 0.
3. Check dbptk-app.log.txt and see how the log mentions EXIT CODE: 0.
4. Execute java -jar dbptk-app-2.11.0-SNAPSHOT.jar validate -if my_valid.siard.
5. Execute echo $?, see how it returns 1.
6. Check dbptk-app.log.txt and see how the log mentions EXIT CODE: 1.