Service remote tool does not import stub package with package prefix

When generating code with package_prefix option, the generated service remote tool does not import generated package with given package prefix.

For example, generate Go code for the following thrift:

namespace go testpkgprefix.api.thrift_gen

service TestPkgPrefix {
	string echo(1: required string msg);
}

with command:

thrift --gen go:package_prefix=repo.local/user/ -out src/repo.local/user -v idl/testpkgprefix.thrift

The resulted Go code will resides in src/repo.local/user/testpkgprefix/api/thrift_gen.

But the import statement of service remote tool ( src/repo.local/user/testpkgprefix/api/thrift_gen/test_pkg_prefix-remote/test_pkg_prefix-remote.go ) will be:

import (
	... // skip
	"testpkgprefix/api/thrift_gen"
	... // skip

instead of:

import (
	... // skip
	"repo.local/user/testpkgprefix/api/thrift_gen"
	... // skip

This issue prevents some tool which does full build (build with ./...) from function normally.