FALCON-2325 Kerberos Service Token refresh does not happen

Author: Pallavi Nagesha Rao <pallavi.rao@im1738-x3.corp.inmobi.com>

Reviewers: @sandeepSamudrala

Closes #398 from pallavi-rao/FALCON-2325 and squashes the following commits:

e0c858a [Pallavi Nagesha Rao] FALCON-2325 Removal of unnecessary whitespace
cce15ea [Pallavi Nagesha Rao] FALCON-2325 Kerberos Service Token refresh does not happen

common/src/main/java/org/apache/falcon/security/AuthenticationInitializationService.java

@@ -157,7 +157,11 @@ public void run() {
             try {
                 LOG.debug("Revalidating Auth Token at : {} with auth method {}", new Date(),
                         UserGroupInformation.getLoginUser().getAuthenticationMethod().name());
-                UserGroupInformation.getLoginUser().checkTGTAndReloginFromKeytab();
+
+                // Relogin does not work in Hadoop 2.6 or 2.7 as isKeyTab check returns false
+                // UserGroupInformation.getLoginUser().checkTGTAndReloginFromKeytab();
+                // Do a regular loginUserFromKeytab, till the issue is addressed.
+                initializeKerberos();
             } catch (Throwable t) {
                 LOG.error("Error in Auth Token revalidation task: ", t);
                 GenericAlert.initializeKerberosFailed("Exception in Auth Token revalidation : ", t);