fix go.mod for Go 1.13 (fullstorydev#110)

add official Dockerfile (fullstorydev#104)

update all deps; use new ResolveFilenames method (fullstorydev#103)

latest protoreflect fixes some bugs in JSON marshaling/unmarshaling (f…

…ullstorydev#86)

use custom flagset (fullstorydev#85)

ignore deprecated check for now (fullstorydev#75)

support go modules (fullstorydev#48)

* support go modules
- use Go 1.11 (with and without module support) in CI
- add go.mod and go.sum files
- with modules in Go 1.11, can't rely on GOPATH directory layout, so just copy test.proto into this repo