started iterator protocol definitions

This is odd behavior:

````julia
julia> [c.timestamp for c in cl][1:3]
3-element Array{Array{Date{ISOCalendar},1},1}:
 [1980-01-03]
 [1980-01-04]
 [1980-01-07]

julia> [c.values for c in cl][1:3]
3-element Array{Array{Float64,1},1}:
 [105.22]
 [106.52]
 [106.81]
````
I wouldn't have expected iterating would create an array of arrays.