Maximize pass

[jlperla]

Optim.jl now supports the univariate maximize function instead of just optimize

We should find all of the places that use optimize and convert to maximize if that is the math implementation. Of course, since this si a move from minimize to maximize, this means swapping the sign of the objective that is passed in as well not swapping the sign of the output

Also, look for http://quantecon.github.io/QuantEcon.jl/latest/api/QuantEcon.html#QuantEcon.golden_method-Tuple{Function,Real,Real} and swap that out as well.

[arnavs]

@XiaojunGuan I think this is a good one to start on. Basically, we have a lot of maximization problems that are coerced into the structure of a minimization problem, because that's what Optim.jl used to support. But now that we've got maximize, we can write them more naturally.

JuliaNLSolvers/Optim.jl#554 is some background on the optimizer, but to see the exact usage you can look at the tests in the Optim package.

[arnavs]

There are 3 left which @XiaojunGuan is having trouble with, so I'll take those.

[Nosferican]

ifp.rst needs a pass.

[Nosferican]

Any update on that?

[arnavs]

Done at e4697c6; thanks for the reminder @Nosferican.