update deutsch-jozsa problem representation

[wrigjl]

The DJ problem description includes a list of function values and a number of bits "n". The latter is unnecessary because it can be inferred from the length of the list which must be a power of 2

$$n = log_2 len(list)$$

Right now, quantumsolver depends on having N readily available, but we should simplify the parsing/representation of this problem AFTER we have the link between Redux and quantumsolver working.

Oh, and while here, rename the "S" variable to "i" to match BV and Simon's problem.

[wrigjl]

A quick update, quantumsolver now either accepts {nbits: 2, f: [0, 1, 0, 1]} or simply [0, 1, 0, 1] as an input, so once #60 is merged, we can simplify the API between redux and qs.