Shaping Up

Requirements now are Golang 1.12+ and Thrift 0.11.0.

New features:
1, Support generating multiple services for GRPC.
2, Support "application/json" for both GRPC API and Thrift API.
3, Config component is refactored.
4, Support GRPC CallOptions.
5, Server component is refactored.
6, Convertors can now be used to create an entire request object.
7, More friendly error messages.
8, Support slices as values in a query string.
9, Support thrift multiplexing.
10, Replace Dep with go modules.

Changes:
1, Param names are case-insensitive
2, "MessageFieldConvertor" is renamed as "Convertor".
3, Fix a concurrent issue: Components must not change when a request is being processed.

TODO:
Get rid of GOPATH env variable.