playground: Change underscore to hyphen for principal tool.

MultiPart: 2/3

Change-Id: Ia65228da39f5d71587cfa1b4ad0b282a19f6e885
diff --git a/client/lib/shell/shell_test.sh b/client/lib/shell/shell_test.sh
index d7f147c..2e2f199 100755
--- a/client/lib/shell/shell_test.sh
+++ b/client/lib/shell/shell_test.sh
@@ -243,7 +243,7 @@
   local -r PRINCIPAL_BIN="$(shell_test::build_go_binary 'v.io/x/ref/cmd/principal')"
   local -r FORKCRED=$(shell::tmp_dir)
   "${PRINCIPAL_BIN}" create --overwrite=true "${FORKCRED}" self >/dev/null || shell_test::fail "line ${LINENO}: create failed"
-  "${PRINCIPAL_BIN}" --veyron.credentials="$1" bless --require_caveats=false "${FORKCRED}" "$2" >blessing || shell_test::fail "line ${LINENO}: bless failed"
+  "${PRINCIPAL_BIN}" --veyron.credentials="$1" bless --require-caveats=false "${FORKCRED}" "$2" >blessing || shell_test::fail "line ${LINENO}: bless failed"
   "${PRINCIPAL_BIN}" --veyron.credentials="${FORKCRED}" set default blessing || shell_test::fail "line ${LINENO}: set default failed"
   "${PRINCIPAL_BIN}" --veyron.credentials="${FORKCRED}" set forpeer blessing ... || shell_test::fail "line ${LINENO}: set forpeer failed"
   echo "${FORKCRED}"