Fix Configuration File Inconsistencies

[akashsinghal]

Description

Please include a summary of the changes and relevant context. Please also reference any related issue in your repository.

• Switch config to using camel case everywhere
• Switch highest level schema of JSON to be singular stores --> store, policies --> policy, verifiers --> verifier

Fixes #233

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Please also list any relevant details for your test configuration

• ran all tests use make test
• deployed to k8s cluster and verified server logs from ratify are correct

Checklist:

• Does the affected code have corresponding tests?
• Are the changes documented, not just with inline documentation, but also with conceptual documentation such as an overview of a new feature, or task-based documentation like a tutorial? Consider if this change should be announced on your project blog.
• Does this introduce breaking changes that would require an announcement or bumping the major version?
• Do all new files have appropriate license header?