Support displaying a privacy notice (#717)

* Support displaying a privacy notice on the log-in UI to implement GDPR measures in the sandbox
* add new property to contain notice
* change login-button text
* Remove demo-login
* pre-fill credentials for demo
* show notice
* introduce `isDemo` variable

Signed-off-by: Jeroen Laverman <jeroen.laverman@bosch-si.com>

hawkbit-runtime/hawkbit-update-server/src/main/resources/application-cloudsandbox.properties

@@ -32,5 +32,12 @@ hawkbit.artifact.url.protocols.md5sum-http.ref=${hawkbit.artifact.url.protocols.
 security.user.name=demo
 security.user.password=demo
 
-hawkbit.server.ui.demo.password=${security.user.name}
 hawkbit.server.ui.demo.user=${security.user.name}
+hawkbit.server.ui.demo.password=${security.user.name}
+hawkbit.server.ui.demo.disclaimer=<small>By signing in, you consent that we store the following data for up to one week: \
+  <ul><li><b>IP-Address:</b> Your client's IP-Address, as well as, the IP-Address of any device you connect to the \
+  application are stored for the purpose of misuse prevention.</li></ul>\
+  <p>You are not permitted to store any kind of personal data in this application, since this is a shared account. \
+  Furthermore, this sandbox is reset once a week deleting all data.</p> \
+  <p><b>Credentials:</b> <code>${hawkbit.server.ui.demo.user}:${hawkbit.server.ui.demo.password}</code></p></small>
+