Add function getGitDescribe

Function getGitCommitDescribe describes commit based on
recent git tag

Change-Id: I2e83923fcfb0800a4a1b5d7b5fc67942d02ed051
diff --git a/src/ci/mcp/Tools.groovy b/src/ci/mcp/Tools.groovy
index 6f4d788..fb552ea 100644
--- a/src/ci/mcp/Tools.groovy
+++ b/src/ci/mcp/Tools.groovy
@@ -100,6 +100,17 @@
 }
 
 /**
+ * Describe a commit using the most recent tag reachable from it
+ */
+def getGitDescribe() {
+    git_commit = sh (
+        script: 'git describe --tags',
+        returnStdout: true
+    ).trim()
+    return git_commit
+}
+
+/**
  * Generate current timestamp
  *
  * @param format    Defaults to yyyyMMddHHmmss