Sample templates: Fix @strings/intro_message

Move @strings/intro_message back from "SingleView" template to
"base" template.

Partially reverts changes from commit
bcbb958aeb9ae6248f6f6865dca506be6d1a1bde.

Change-Id: Iffa639a9334e3738ab6fd93985884ea46d43c614
2 files changed