"core": Shell tests must use the agent

This CL moves the veyron/tool/mgmt and veyron/services/identity
shell tests so that they only use a principal supplied by the agent
(as opposed to the VEYRON_CREDENTIALS directory).

With this CL, all shell tests in the core package would switch to
using the agent.

Change-Id: I986a646381d2b129698402f7fe82f9730b3b6a0c
diff --git a/services/identity/test.sh b/services/identity/test.sh
index 5b30587..471e140 100755
--- a/services/identity/test.sh
+++ b/services/identity/test.sh
@@ -4,6 +4,9 @@
 
 source "$(go list -f {{.Dir}} v.io/core/shell/lib)/shell_test.sh"
 
+# Run the test under the security agent.
+shell_test::enable_agent "$@"
+
 readonly WORKDIR="${shell_test_WORK_DIR}"
 
 build() {
@@ -32,14 +35,12 @@
 main() {
   cd "${WORKDIR}"
   build
-
+ 
   shell_test::setup_server_test || shell_test::fail "line ${LINENO} failed to setup server test"
-  unset VEYRON_CREDENTIALS
 
   # Start the identityd server in test identity server.
-  shell_test::start_server "${IDENTITYD_BIN}" --host=localhost -veyron.tcp.address=127.0.0.1:0
+  shell_test::start_server "${VRUN}" "${IDENTITYD_BIN}" --host=localhost -veyron.tcp.address=127.0.0.1:0
   echo Identityd Log File: $START_SERVER_LOG_FILE
-  export VEYRON_CREDENTIALS="$(shell::tmp_dir)"
 
   # Test an initial seekblessings call, with a specified VEYRON_CREDENTIALS.
   WANT="Received blessings"