text: Title: [bug] In Python 3.4 and below inspect.stack() returns just a tuple in the list, not a list of named tuples
  Body: **Describe the bug**
  In Python 3.4 and below `inspect.stack()` returns just a tuple in the list, not a list of named tuples. Only since version 3.5 does it return a list of named tuples.
  
  **To Reproduce**
  Steps to reproduce the behavior:
  
  1. Having the following folder structure
  
  <!-- Describe or use the command `$ tree -v` and paste below -->
  
  <details>
  <summary> Project structure </summary>
  
  ```bash
  
  # example.py
  # settings.ini
  
  ```
  </details>
  
  2. Having the following config files:
  
  <!-- Please adjust if you are using different files and formats! -->
  
  <details>
  <summary> Config files </summary>
  
  **settings.ini**
  ```ini
  [default]
  path = 'example.txt'
  ```
  
  </details>
  
  3. Having the following app code:
  
  <details>
  <summary> Code </summary>
  
  **example.py**
  ```python
  from dynaconf import settings
  
  print(settings.PATH)
  ```
  
  </details>
  
  4. Executing under the following environment
  
  <details>
  <summary> Execution </summary>
  
  ```bash
  $ python example.py
  
  Traceback (most recent call last):
    File "example.py", line 3, in <module>
      print(settings.PATH)
    File "C:\Python\Python34\lib\site-packages\dynaconf\base.py", line 93, in __getattr__
      self._setup()
    File "C:\Python\Python34\lib\site-packages\dynaconf\base.py", line 118, in _setup
      default_settings.reload()
    File "C:\Python\Python34\lib\site-packages\dynaconf\default_settings.py", line 74, in reload
      start_dotenv(*args, **kwargs)
    File "C:\Python\Python34\lib\site-packages\dynaconf\default_settings.py", line 61, in start_dotenv
      or _find_file(".env", project_root=root_path)
    File "C:\Python\Python34\lib\site-packages\dynaconf\utils\files.py", line 62, in find_file
      script_dir = os.path.dirname(os.path.abspath(inspect.stack()[-1].filename))
  AttributeError: 'tuple' object has no attribute 'filename'
  ```
  
  </details>
  
  **Expected behavior**
  ```python
  from dynaconf import settings
  
  print(settings.PATH)
  # 'example.txt'
  ```
  
  **Debug output**
  
  <details>
  <summary> Debug Output </summary>
  
  ```bash
  
  export `DEBUG_LEVEL_FOR_DYNACONF=DEBUG` reproduce your problem and paste the output here
  2019-08-26:16:46:23,988 DEBUG    [default_settings.py:55 - start_dotenv] Starting Dynaconf Dotenv Base
  2019-08-26:16:46:23,989 DEBUG    [files.py:57 - find_file] No root_path for .env
  Traceback (most recent call last):
    File "example.py", line 3, in <module>
      print(settings.PATH)
    File "C:\Python\Python34\lib\site-packages\dynaconf\base.py", line 93, in __getattr__
      self._setup()
    File "C:\Python\Python34\lib\site-packages\dynaconf\base.py", line 118, in _setup
      default_settings.reload()
    File "C:\Python\Python34\lib\site-packages\dynaconf\default_settings.py", line 74, in reload
      start_dotenv(*args, **kwargs)
    File "C:\Python\Python34\lib\site-packages\dynaconf\default_settings.py", line 61, in start_dotenv
      or _find_file(".env", project_root=root_path)
    File "C:\Python\Python34\lib\site-packages\dynaconf\utils\files.py", line 62, in find_file
      script_dir = os.path.dirname(os.path.abspath(inspect.stack()[-1].filename))
  AttributeError: 'tuple' object has no attribute 'filename'
  ```
  
  </details>
  
  **Environment (please complete the following information):**
   - OS: Windows 8.1
   - Dynaconf Version 2.0.4
   - Python Version 3.4.3
  