Fix: Handle trailing slash on Appliance URL

[doodlesbykumbi]

Desired Outcome

Depends on cyberark/conjur-api-go#179, which updates conjur-api-go to seamlessly handle traling slashes on the Appliance URL

This PR

1. Adds an integration test for init and login using an Appliance URL with a trailing slash
2. Updates go.mod files to use the new version of conjur-api-go

Implemented Changes

Describe how the desired outcome above has been achieved with this PR. In
particular, consider:

• What's changed? Why were these changes made?
• How should the reviewer approach this PR, especially if manual tests are required?
• Are there relevant screenshots you can add to the PR description?

Connected Issue/Story

Resolves #[relevant GitHub issue(s), e.g. 76]

CyberArk internal issue ID: [insert issue ID]

Definition of Done

At least 1 todo must be completed in the sections below for the PR to be
merged.

Changelog

• The CHANGELOG has been updated, or
• This PR does not include user-facing changes and doesn't require a
  CHANGELOG update

Test coverage

• This PR includes new unit and integration tests to go with the code
  changes, or
• The changes in this PR do not require tests

Documentation

• Docs (e.g. READMEs) were updated in this PR
• A follow-up issue to update official docs has been filed here: [insert issue ID]
• This PR does not require updating any documentation

Behavior

• This PR changes product behavior and has been reviewed by a PO, or
• These changes are part of a larger initiative that will be reviewed later, or
• No behavior was changed with this PR

Security

• Security architect has reviewed the changes in this PR,
• These changes are part of a larger initiative with a separate security review, or
• There are no security aspects to these changes

[codeclimate]

Code Climate has analyzed commit 8f0bc2b and detected 0 issues on this pull request.

The test coverage on the diff in this pull request is 100.0% (50% is the threshold).

This pull request will bring the total coverage in the repository to 82.3% (0.0% change).

View more on Code Climate.

[szh]

LGTM

[UberKitten]

Finally! This has been so annoying, especially since there wasn't an obvious error.