[Data collection] Date/time/number fields don't respect user's preferred formats

[gino-m]

We should use android.text.format.DateFormat.getDateFormat(context), but DateResponse and TimeResponse are context-agnostic. Formatting should instead be done in the view layer, with the response objet's String representation used for debugging only. Fyi @HemanParbhakar, discussed in #749.

[gino-m]

@HemanParbhakar Would you like to tackle this one once #846 is merged?

[scolsen]

@shobhitagarwal1612 assigning to you for now, please reassign if needed!