Output lookml results as json

[nickdeis]

Change description

Adds the flag --json, that allows you to output lookml results as raw json

Type of change

• Bug fix (fixes an issue)
• New feature (adds functionality)

Security

• Security impact of change has been considered
• Code follows security best practices and guidelines

Code review

• Pull request has a descriptive title and context useful to a reviewer

[joshtemple]

Hey @nickdeis, thanks for this! Could you expand this so the --json option works for all subcommands? (e.g. spectacles sql, spectacles content, etc.)