Adding debug target on Makefile, fixing leaderElection and imageConfi…

[vitorguidi]

…gFile reference

What this PR does: This PR adds the make debug directive, which allows developers to attach the debugger to delve locally in port 2345. It also fixes the config files for the manager and container images, to correctly load the default operator config, and allow for properly downloading the cassandra container images.

Which issue(s) this PR fixes: Fixes #610

Checklist

• [ ] Changes manually tested
• [ ] Automated Tests added/updated
• [ ] Documentation added/updated
• [ ] CHANGELOG.md updated (not required for documentation PRs)
• [ ] CLA Signed: DataStax CLA

[burmanm]

Hey, slipped a bit under my radar. The debug targets in Makefile are alright, but the config changes are not. The /configs is the intended default location and we want to keep leaderElection enabled by default.