Use simpleserializer with TypeLayer

[keith-turner]

After #82 I think it may make sense to drop the Encoder used by the TypeLayer and instead use the SimpleSerlializer. This will result in a more uniform and consistent user experience. It will also allow the addition of set(Object) and T toObject(Class<T> clazz) methods.

SimpleConfiguration appConfig = ...
Transaction tx = ...
//The serialzer implementation is read from app config
TypeLayer tl = ...
TypedTransaction ttx = tl.wrap(tx);

String r = ...;
String f = ...;
long q = ...;

//some pojo type
SomePojo sp = ... 

ttx.mutate().row(r).fam(f).qual(q).set(sp)
SomePojo sp2 = ttx.get().row(r).fam(f).qual(q).toObject(SomePojo.class)

//get with default value
SomePojo default = ...
SomePojo sp3 = ttx.get().row(r).fam(f).qual(q).toObject(SomePojo.class, default)

There are some things I am uncertain about. First I was thinking that one SimpleSerializer should replace Encoder, but then I thought about the case where want to encode key fields differently than values. For example may want to encode long types in row, family and qualifier in a certain way so that they sort properly. Also, I am thinking it should be possible to use config to get class types.

One option could be to drop encoder, replacing it with simplerserializer and optionally support using a different type of simpleserializer for key fields. This could possible be done with a builder pattern. I am not sure if I like this approach yet.

//build a type layer getting key and value SimpleSerializer type from config. 
tl = TypeLayer.builder().config(...).build()

//build a type layer with a specific SimpleSerializerfor keys and get the simple serializer for values from config
tl = TypeLayer.builder().keySerializer(....).config(....).build()