Updated PWL assets for Twitter, etc.

[DarrenN]

@Randommood we put together a new set of PWL assets for SFO -> https://www.dropbox.com/s/7adpah3hhtksnmd/pwl-sfo.zip?dl=0

These include the service mark for PWL, and identifiers for San Francisco.

Thanks!

[akshayjshah]

I'll take this one :)