text: Title: Zip file - Windows paths
  Body: <!--- Provide a general summary of the issue in the Title above -->
  ## Context
  When deploying a Django app (over 50mb) from a Windows 10 machine the tarball retains the Windows directory separators '\\\\', when deployed to Lambda this causes the error  "No module named 'django.core.wsgi': ModuleNotFoundError"
  
  ## Expected Behavior
  1.  tarball should keep Unix directory separators
  
  ## Actual Behavior
  1. tarball retains Windows directory separators
  
  ## Possible Fix
  In core.py, line 683 can be replaced with:
  
  `tarinfo = tarfile.TarInfo(posixpath.join(root.replace(temp_project_path, '').lstrip(os.sep).replace('\\', '/'), filename))`
  
  Which fixed it for me but is quite hacky and probably not that robust.
  
  ## Steps to Reproduce
  <!--- Provide a link to a live example, or an unambiguous set of steps to -->
  <!--- reproduce this bug include code to reproduce, if relevant -->
  1.` zappa deploy dev ` on Windows 10 machine with app over 50mb 
  
  ## Your Environment
  * Zappa version used: 0.45.1
  * Operating System and Python version: Windows 10, Python 3.6
  * Your `zappa_settings.py`: 
  
  ```
  {
      "dev": {
          "aws_region": "us-east-2",
          "django_settings": "<redacted>",
          "profile_name": "default",
          "project_name": "<redacted>",
          "runtime": "python3.6",
          "s3_bucket": "<redacted>",
          "exclude": ["*.env", "*.jpg", "*.png", "media*", "archive*", "node_*", ],
          "slim_handler": true,
          "timeout_seconds": 300,
      }
  }
  ```
  