update attach property for sender/receiver (#22)
* update attach property
so that the spring-boot is deployed.
If attach is set to false, the deployed jar is not usable ( will only contain artifacts from dbsync-receiver-app)
* add property classifier
The property classifier is added to publish the executable jar with another complete artifact id
* remove attach=true
remove 'attach=true' as it's the default value
* - modify the sping-boot configuration for sender and receiver: add classifier exe to generate 2 jar ( executable and normal)
- update documentation accordingly to these modification
- add source version to example-app ( to let it be compiled)
