fails compliance tests for benchmarks, functions, literal, and syntax.

Go version of jmespath is failing compliance tests in the following suites: benchmarks, functions, literal, and syntax.

The python version fails only in benchmarks suite.

See also: https://github.com/jmespath/go-jmespath/issues/33
```
% jp -v
jp version 0.1.3

% jp-compliance -e jp -t benchmarks
'error'

% jp-compliance -e jp -t functions
.................
FAIL functions,0,17
The expression: avg(empty_list)
was suppose to give: null
for the JSON: {"foo": -1, "zero": 0, "numbers": [-1, 3, 4, 5], "array": [-1, 3, 4, 5, "a", "100"], "strings": ["a", "b", "c"], "decimals": [1.01, 1.2, -1.5], "str": "Str", "false": false, "empty_list": [], "empty_hash": {}, "objects": {"foo": "bar", "bar": "baz"}, "null_key": null}
but instead gave: ""
..........................................................................................................................................................
FAIL

% jp-compliance -e jp -t literal
........................................
FAIL literal,2,12
The expression: '\\'
was suppose to give: "\\\\"
for the JSON: {}
but instead gave: ""
FAIL

% jp-compliance -e jp -t syntax
...............................................
FAIL syntax,8,1
The expression: [:::]
was suppose to have non zero for error error: syntax
but instead gave rc of: 0, stderr:
.....................................................................................
OK
```