Allow Strategy template trading_logic! implementations to behave differently with respect to the format of the data received

[brunocastroibarburu94]

It would be nice if the strategy templates may be compatible with more than one format of data, and it would also be nice if it didn't take much effort to do it.

Design comments: Julia has Typing on datatypes for example 2USD can have the type Money{:USD} and we can have a function

function x(m::Money{S}) where {S} 
  if S==:USD
   # Do this
  end
end

Even more you can have multiple dispatch depending on the value of S. This can be a nice computational advantage if implemented correctly

[brunocastroibarburu94]

Not sure which milestone this would correspond to, nor how it prioritize against other stories. Will leave in the parking lot in the meantime