OPA conformance tests (#45)

Run regorus against OPA test suite.

To run full test suite:
  cargo test --test opa

To run specific folder (e.g semver):
  cargo test --test opa -- semver

Signed-off-by: Anand Krishnamoorthi <anakrish@microsoft.com>

tests/tests.rs

@@ -3,7 +3,6 @@
 
 mod interpreter;
 mod lexer;
-mod opa;
 mod parser;
 mod scheduler;
 mod value;