ts parameter and p='{x}d' parameter

[troymaclure]

According to :
http://www.networkerror.org/component/content/44.html?task=view

ts - Starting timestamp (Unix format). If blank, it uses today.

and

p - Period. (A number followed by a "d" or "Y", eg. Days or years. Ex: 40Y = 40 years.)

Which, used together allow to fine tune the date range of the data, ease the use of the downloaded file and make the library convenient for use cases involving data not starting from today.

In the current state of affair, we can process the returned dataframe in order to get only the desired range, but it's an unecessary waste of computional ressource and require to use a wrapper to make good use of the library beyond a single case.

The package should be modified in order to take that into account.

[troymaclure]

Would you integrate it with a pull request?