Add compliance tests for non number comparisons

From the spec
(http://jmespath.org/specification.html#ordering-operators):

> Ordering operators >, >=, <, <= are only valid for numbers. Evaluating
> any other type with a comparison operator will yield a null value, ...

Author: jamesls

tests/compliance/boolean.json

@@ -205,7 +205,9 @@
     "given": {
       "one": 1,
       "two": 2,
-      "three": 3
+      "three": 3,
+      "emptylist": [],
+      "boolvalue": false
     },
     "cases": [
       {
@@ -236,6 +238,22 @@
         "expression": "one != two",
         "result": true
       },
+      {
+        "expression": "emptylist < one",
+        "result": null
+      },
+      {
+        "expression": "emptylist < nullvalue",
+        "result": null
+      },
+      {
+        "expression": "emptylist < boolvalue",
+        "result": null
+      },
+      {
+        "expression": "one < boolvalue",
+        "result": null
+      },
       {
         "expression": "one < two && three > one",
         "result": true