Created NeweggAPI class to simplify querying newegg

Separated the code to query newegg. This will make pages much cleaner in
the long run and will get rid of lots of duplicated code.

Updated Televisions.aspx to use the NeweggAPI.

Basic usage:
NeweggAPI api = new NeweggAPI();
List<SubCategory> televisions =
api.GetCategoryByName("Electronics").GetSubCategoryByName("Televisions").GetSubCategories();
ProductQuery products = televisions[0].QueryProducts();
Categorygrid.DataSource = products.ProductListItems;