Remove go modules

[yurishkuro]

According to jaegertracing/jaeger-lib#75 (comment), enabling go modules is more complicated when the library is on a version above 1.x, which is the case with jaeger-client-go and jaeger-lib.

For now, removing go modules. Will revisit in the future along with potential renaming of the path from /uber/ to /jaegertracing/

Reopens #382

[codecov]

Codecov Report

Merging #425 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #425   +/-   ##
=======================================
  Coverage   92.06%   92.06%           
=======================================
  Files          22       22           
  Lines        1625     1625           
=======================================
  Hits         1496     1496           
  Misses         87       87           
  Partials       42       42

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[F21]

It looks like the go.mod and go.sum files were not removed, so the latest release (2.18.0) can't be installed using go modules.

[yurishkuro]

The previous releases couldn't be installed with go modules either.

[F21]

2.17.0 is installable as v2.17.0+incompatible because there are no go.mod and go.sum files in the release: https://github.com/jaegertracing/jaeger-client-go/tree/85825f3f682a6fb24b12a4604be2a101432c7534

2.18.0 fails with go get github.com/uber/jaeger-client-go@v2.18.0: github.com/uber/jaeger-client-go@v2.18.0: invalid version: module contains a go.mod file, so major version must be compatible: should be v0 or v1, not v2

[yurishkuro]

Ah, sorry, I see what you mean. I will remove mod files and do another release.