Project ID's are hard-coded in tests

[buep]

When running tests, using the SD Elements service you supply URL and API token to the tests, pointing it to your service.
The project ID are hard-coded though: https://github.com/Praqma/sdelements-plugin/blob/master/src/test/java/io/jenkins/plugins/sdelements/SDElementsTest.java#L72

They need to be changed for other to run the tests, so they should be extracted out into configuration together with API token and server URL to allow different users to configure their tests.