Increment dm release to r4. 
Updated README to remind that the ext.dmRelease has to be incremented before making a release.


git-svn-id: https://svn.apache.org/repos/asf/felix/trunk@1683635 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/dependencymanager/release/build.gradle b/dependencymanager/release/build.gradle
index 9fd512a..87fc467 100644
--- a/dependencymanager/release/build.gradle
+++ b/dependencymanager/release/build.gradle
@@ -23,7 +23,7 @@
 import aQute.bnd.build.Workspace
 
 // Our release number, which has to be monotonically incremented each time we make a new release.
-ext.dmRelease = "r3"
+ext.dmRelease = "r4"
 
 // Our Apache svn Staging repo
 ext.svnStagingPath = "https://dist.apache.org/repos/dist/dev/felix"