twitter-demo: fix usage of shared_ptr
twitter-demo: fix usage of shared_ptr

d84d860243c5ff30158cddb02c477925774f7db5 removed 'using std::tr1::shared_ptr'
from a number of header files. For some reason on my system this caused the
twitter demo to no longer compile due to an unqualified shared_ptr reference.

This adds the necessary directive.

Change-Id: Ic5538a652f71a24650529952dc14fe0010c4fe75
Reviewed-on: http://gerrit.cloudera.org:8080/1446
Reviewed-by: Mike Percy <e07a1fd797b473a9c849e618aa2ce06d8055760b@cloudera.com>
Reviewed-by: Dan Burkert <2591e5f46f28d303f9dc027d475a5c60d8dea17a@danburkert.com>
Tested-by: Internal Jenkins

InspurUSA/kudu,EvilMcJerkface/kudu,helifu/kudu,andrwng/kudu,andrwng/kudu,EvilMcJerkface/kudu,andrwng/kudu,helifu/kudu,helifu/kudu,cloudera/kudu,InspurUSA/kudu,cloudera/kudu,helifu/kudu,andrwng/kudu,EvilMcJerkface/kudu,InspurUSA/kudu,andrwng/kudu,cloudera/kudu,EvilMcJerkface/kudu,EvilMcJerkface/kudu,andrwng/kudu,InspurUSA/kudu,EvilMcJerkface/kudu,InspurUSA/kudu,andrwng/kudu,helifu/kudu,EvilMcJerkface/kudu,EvilMcJerkface/kudu,InspurUSA/kudu,helifu/kudu,andrwng/kudu,helifu/kudu,cloudera/kudu,cloudera/kudu,EvilMcJerkface/kudu,InspurUSA/kudu,cloudera/kudu,helifu/kudu,helifu/kudu,cloudera/kudu,cloudera/kudu,InspurUSA/kudu,cloudera/kudu,andrwng/kudu,InspurUSA/kudu