syncbase: add code for todos app, with store stubbed out

- migrates code from $V23_ROOT/deprecated/go/src/v.io/examples/todos
- removes lots of cruft, leaving just the webapp
- cleans up Makefile and friends
- updates third-party JS deps to latest versions
- fixes a few minor bugs in webapp

Change-Id: I6f210bfa4f0d9c4cb9d905c416aaf72d4e633b34
22 files changed