Enabling Auto-Export creates incorrect properties for Taxonomy Plugin Demo

[tobi - additional context]: The taxonomy demo project has auto-export disabled by default, overriding the repository project's default (true). When enabling auto-export in the Console, I would expect that auto-export recognizes that the property now has the default value as defined in the repository project, and therefore remove the property definition from the demo project's YAML Source. Instead, it adjusts the property definition's value (to true), which leads to the WARN messages documented below.

Steps to Reproduce:

1. Clone hippo-plugin-taxonomy from GitLab
2.  Checkout branch release/4.0 
3. Use Maven to build and run the DEMO project
4. Launch CMS and Switch on Auto-Export
5. Build & Run the Demo again
6. Launch CMS and edit or create new Taxonomy category under Taxonomy Type.

Expected: Auto-Export logs should be generated.

Actual: Logs generated

[INFO] [talledLocalContainer] 31.10.2017 12:51:31 WARN pool-9-thread-1 [ConfigurationTreeBuilder.warnIfValuesAreEqual:712] Property '/hippo:configuration/hippo:modules/autoexport/hippo:moduleconfig/autoexport:enabled' defined in 'demo/demo/repository [config: configuration/modules/autoexport-module.yaml]' specifies value equivalent to existing property, defined in '[hippo-cms/hippo-repository/hippo-repository-engine [config: autoexport-module.yaml]]'.

Root Cause:

__Property created as autoexport:enabled: true in autoexport-module.yaml at hippo-plugin-taxonomy/demo/repository-data/src/main/resources/hcm-config/configuration/modules where as default property of Auto-Export ON is already exists at  '/hippo:configuration/hippo:modules/autoexport/hippo:moduleconfig/autoexport:enabled'