Prepare v0.30.0 release (open-policy-agent#662)

Signed-off-by: John Reese <[email protected]>

Do not make rego trace unless --trace flag is passed in (open-policy-…

…agent#556)

* Making tracing functionality optional

Signed-off-by: Sarvar Muminov <[email protected]>

* Adding tests

Signed-off-by: Sarvar Muminov <[email protected]>

* Use Trace variable for `verify` command

Signed-off-by: Sarvar Muminov <[email protected]>

Push images on release