[#68924438] added 'download prices' feature
[#68924438] added PricesController#download
[#68924438] added PricesDownloader and started the spec
[#68924438] added logic to PriceDownloader to get pricess from an agent and save them
[#68924438] finished changes to PricesController
[#68924438] finished making 'download prices' feature pass
[#68924438] moved stock price classes to lib
[#68924438] added unit test for memory download agent
[#68924438] started adding spec for quandl download agent
[#68924438] fixed references to PriceDownloader
[#68924438] finished quandl download agent initial implementation
[#68924438] styled the download button
[#68924438] added configuration to StockPrices module
[#68924438] added Commodity#lots
[#68924438] added DreamDownloadAgent and stock prices initializer
[#68924438] made trade date unique for commodity prices
[#68924438] adjusted app to avoid duplicate price records
refined the quandl download agent