Add baiji4j implementation.
add the JsonSerializer.....
Add guava into dependencies.
Support explicit value in EnumSchema.
Add addField method.
Add rpc projects.
Remove canRead methods.
add json-encoder....
add the json writer/reader....
know where to go....
update the encoder&serializer
update the JsonEncoder...
refactor SpecificJsonWriter....
refactor the code...
add the write bytes...
add the write array...
add write enum....
add write map....
little update....
add write union....