[Feature] Datetime support

[Vichoko]

It could be great if -bd and -ed parameters could be Datetime fields instead of just Date.
Because in some cases the minimum resolution (1 day) is too big to capture all the tweets in just one twitterscrapper. For example when an important event occur it's common that the twitter count rises.

I think maybe it isn't that difficult to implement and could be a great feature for these cases, as the command doesn't deliver partial results or a way to resume a failed scrap. Also there is no ETA or expected tweet number, so the usage time and limit parameter can be a little unpredictable.

[TrueCarry]

Hello. I've created pull request with that feature. You can try my fork #258