adding the ability to build queries in stages

[slorello89]

Addresses #78,

Allows users to build their queries in stages. Previously, Redis OM .NET would only honor the last boolean query passed to it. So if you queried

collection.Where(x=>x.FirstName == "Alice").First(x=>x.Age < 32);

Only all the people younger than 32 would be returned from the collection. With this PR, both queries are cleanly folded together to make one query to Redis.

The methodology for this is that the collection now keeps track of all Expression<Func<T,bool>> passed to it over time, folding them all together into something usable.