Adding new scrapers

Town Crier has been developed to make adding new datasources as simple as possible. The Scraper interface has one function handle_event that is responsible for handling any requested event. To add a Scraper class, simply make it a subclass of the Scraper interface and provide an implementation of for handle_request

To add a new scraper:

1. Under /src/Common/Constants.h add a new Macro for the event
2. Handle the even in /src/Enclave/event_handler.cpp by adding a new case
3. Add the new scraper object to the /src/Enclave/scrapers folder and make sure that it is a subclass of the Scraper.h interface
4. Add unit tests for this scraper in the /src/Enclave/test folder
5. Compile and test

** List of Events that town crier currently supports (Updated 5/14/2017) **

Each of these contains a handle class that returns a desired value. We describe the structure of the input data below: SteamTrade: Input: 0x00 - 0x40 Enc API key 0x40 - 0x60 buyer ID 0x60 - 0x80 wait time 0x80 - 0xa0 item len 0xa0 - 0xc0 Output: Returns 1 if the trade has been found, 0 otherwise

StockTicker:
	Input:
		0x00 - 0x20 Symbol (i.e GOOG, APPL, etc)
		0x20 - 0x40 ascii Month 
		0x40 - 0x60 ascii Day
		0x60 - 0x80 ascii Year
	Output:
		32 bytes - Closing Price


FlightInsurance:
	Input:
       	0x00 - 0x20 string flight_number
       	0x20 - 0x40 uint64 unix_epoch
	Output:
		32 byte- delay time in epoch time 
		Note: If the flight has not departed yet then returns 0
		
UPSTracking:
	Input:
		0x00 - 0x20 string tracking number
	Output:
		32 byte integer, indicating the status of the Package, the ints are,
		   -1  - ERROR
			0  - PACKAGE_NOT_FOUND,
			1  - ORDER_PROCESSED,
			2  - SHIPPED,
			3  - IN_TRANSIT,
			4  - OUT_FOR_DELIVERY,
			5  - DELIVERED,

CoinMarketScraper:
	Description: Gives the current exchange rate in dollars for a given crypto-currency
	Input:
		0x00 - 0x20 string cryptocurrency
	Output:
		32 bit integer indicating the currentn exchange rate of the package