Add a method to get historical 52-week high

[usvyatsky]

I have a small enhancement to the package that computes a historical 52-week high.
The definition of a historical 52-week high I used is as follows:
The highest 'High' of all prices of a given symbol in a 1-year range than ends at a specified date.
The function returns a dict of dicts (just like original get_historical_prices) which usually contains a single element with the date as a key and a full data dictionary of that dates data as a value.
In a rare case of more than one occasions of the same highest 'High' value within the period all those occasions are included in the result.
I will create a pull request with my enhancement shortly.