Add semantic label to the TwitterMap demo

[JavierJia]

we can research on the existing NLP package to see if the semantic analysis can be done offline or it has to be labeled.

@thejdeep

[chenlica]

I have sent an introduction email to another student, Phanwadee, who is doing something similar. Let's do the discussion by email first. If needed, @JavierJia please schedule a meeting with Phanwadee.