Fix ST3 ImportError

After installing the package in ST3 build 3012, I got the following error in the console. This commit imports differently if the current method fails.

```bash
Traceback (most recent call last):
  File "E:\PortableApps\SublimeText3\sublime_plugin.py", line 68, in reload_plugin
    m = imp.reload(m)
  File "X/imp.py", line 252, in reload
  File "<frozen importlib._bootstrap>", line 586, in _check_name_wrapper
  File "<frozen importlib._bootstrap>", line 1023, in load_module
  File "<frozen importlib._bootstrap>", line 1004, in load_module
  File "<frozen importlib._bootstrap>", line 562, in module_for_loader_wrapper
  File "<frozen importlib._bootstrap>", line 854, in _load_module
  File "<frozen importlib._bootstrap>", line 981, in get_code
  File "<frozen importlib._bootstrap>", line 313, in _call_with_frames_removed
  File "E:\PortableApps\SublimeText3\Data\Packages\FindKeyConflicts\find_key_conflicts.py", line 9
    from minify_json import json_minify
```