bumped TravisCI go version to 1.12

Merge remote-tracking branch 'origin/master' into ozon

Merge remote-tracking branch 'origin/master' into ozon

Merge pull request utrack#65 from bullgare/default-set-error

Customizable http errors for grpc errors

Merge pull request utrack#61 from makhov/remove-error-wrapper

removing handler error wrapper

Merge pull request utrack#60 from doroginin/impl_file_name_tmpl

Add impl_file_name_tmpl param for implementation's filename mutation

Merge pull request utrack#59 from doroginin/http.499

Fix error: `http: multiple response.WriteHeader calls`

Merge pull request utrack#58 from doroginin/fix.imports

Fix imports in case of no http mapping

Now transport.WithUnaryInterceptor autostacks the middlewares; update…

…d grpc to v1.16.0

Merge pull request utrack#55 from eaglemoor/LIBS-177

[LIBS-177] up gogoproto