Add annotation support to POJO Mappers.

Let's introduce annotations for mapper builder.

Suggested annotations:

• Transient - that makes mapper ignore the marked field. Field data will not be saved into a table.
• Column(String) - maps field to a field of the given name.
• Column(Class) - maps field to a field of given name using converter class.

This will allow users to create mapper like this

class Record {
    @Transient
    transient Object cachedData;

   @Column(UserMarshaller.class)
    UseObject value;

    @Column("key")
    UUID id;
}

Mappers.forClass(Record.class)

instead of like this

 Mappers.of(Record.class)
    .map("id", "key")
    .map("value", 
        (obj) -> Marshaller.marshal(obj), 
        (row) -> Marshaller.unmarshal(row)
    );