Merge pull request #2165 from batmat/install-text-leaner

More concise welcome text for Jenkins 2

core/src/main/resources/jenkins/install/UpgradeWizard/footer.properties

-msg.before=Welcome to Jenkins v2!\u0020
-msg.link=Click here to install the rest of v2 functionalities
-msg.after=\u0020and finish the upgrade process
\ No newline at end of file
+msg.before=Welcome to Jenkins 2!\u0020
+msg.link=Click here to install additional features
+msg.after=\u0020and finish the upgrade process