Add variable get/set/delete commands.
Remove --search option, people can use | grep.
Improve output for multiple variables.

Use --pipe, or just pipe into another command like grep, for full & clean
output.
More informative errors for the variable:delete command.
Fix bug with --ssh and JSON values.
Cleanup, including renaming Resource to HalResource to avoid type hint issues.
Merge pull request #161 from pjcdawkins/feature/variables

Add variable get/set/delete commands.