Add gorm plugin

[AFMiziara]

Adding protoc-gen-gorm to the image.

[rvolosatovs]

LGTM, thanks!

[rvolosatovs]

Hmm, looks like CI is not too happy:

 > [linux/amd64 protoc_gen_gorm  2/11] RUN curl -sSL https://api.github.com/repos/infobloxopen/protoc-gen-gorm/tarball/v${PROTOC_GEN_GORM_VERSION} | tar xz --strip 1 -C /go/src/github.com/infobloxopen/protoc-gen-gorm:
#0 5.750 tar: invalid magic
#0 5.750 tar: short read
------
Dockerfile:116
--------------------
 114 |     RUN mkdir -p ${GOPATH}/src/github.com/infobloxopen/protoc-gen-gorm
 115 |     ARG PROTOC_GEN_GORM_VERSION
 116 | >>> RUN curl -sSL https://api.github.com/repos/infobloxopen/protoc-gen-gorm/tarball/v${PROTOC_GEN_GORM_VERSION} | tar xz --strip 1 -C ${GOPATH}/src/github.com/infobloxopen/protoc-gen-gorm
 117 |     WORKDIR ${GOPATH}/src/github.com/infobloxopen/protoc-gen-gorm
 118 |     RUN mkdir /protoc-gen-gorm-out
--------------------
error: failed to solve: process "/bin/sh -c curl -sSL https://api.github.com/repos/infobloxopen/protoc-gen-gorm/tarball/v${PROTOC_GEN_GORM_VERSION} | tar xz --strip 1 -C ${GOPATH}/src/github.com/infobloxopen/protoc-gen-gorm" did not complete successfully: exit code: 1

Could you take a look?