Implement NFL Weekly Schedule

Implement the NFL [Weekly Schedule from the Sports Data API](http://developer.sportsdatallc.com/docs/NFL_API)

# Weekly Schedule

###### Schema 

Syntax: `http://api.sportsdatallc.org/nfl-[access_level][version]/schema/schedule-v1.0.xsd?api_key=[your_api_key]`

[Schema Example](http://api.sportsdatallc.org/nfl-t1/schema/schedule-v1.0.xsd?api_key=p94qrfyum52x5422aa9r5yd3)

###### Feed 

Syntax: `http://api.sportsdatallc.org/nfl-[access_level][version]/[year]/[nfl_season]/[nfl_season_week]/schedule.[format]?api_key=[your_api_key]`

###### Parameter Format Notes

`[access_level] = Real-Time (rt), Premium (p), Standard (s), Basic (b), Trial (t)`

`[version] = whole number (sequential, starting with the number 1)`

`[year] = yyyy`

`[nfl_season] = Preseason (PRE), Regular Season (REG), Postseason (PST)`

`[nfl_season_week] = 1 - 17 (Week 0 of Preseason is Hall of Fame game)`

`[format] = xml`

[Feed Example](http://developer.sportsdatallc.com/files/nfl_v1_weekly_schedule_example.xml)