refactor(build): Migrating from dep to Go modules

[RealHarshThakur]

Why is this PR required? What issue does it fix?:
Go modules is a better dependency management than dep.

What this PR does?:
Migrates to use Go modules

Does this PR require any upgrade changes?:

• go version is upgraded to 1.14
• Goinkgo and Gomega packages were upgraded

If the changes in this PR are manually verified, list down the scenarios covered::
Works on go 1.13 and 1.14

Steps performed :

• go mod init
• go mod tidy
• Upgraded gomega and goinkgo to latest version to fix fsnotify error
• Added go mod tidy and god mod verify in the Makefile
• Removed gopkg.toml and gopkg.lock
• Run integration test with sudo in .travis.yml
• go mod vendor

Checklist:

• Fixes #
• PR Title follows the convention of <type>(<scope>): <subject>
• Has the change log section been updated?
• Commit has unit tests
• Commit has integration tests
• (Optional) Are upgrade changes included in this PR? If not, mention the issue/PR to track:
• (Optional) If documentation changes are required, which issue on https://github.com/openebs/openebs-docs is used to track them:

[codecov-commenter]

Codecov Report

Merging #434 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #434   +/-   ##
=======================================
  Coverage   43.63%   43.63%           
=======================================
  Files          61       61           
  Lines        2947     2947           
=======================================
  Hits         1286     1286           
  Misses       1559     1559           
  Partials      102      102           

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[akhilerm]

changes looks good.

please update the docs in a follow up PR.