text: Title: Can't parse ".serverless/requirements/xlrd/biffh.py" unless encoding is latin
  Body: <!--- Provide a general summary of the issue in the Title above -->
  ## Context
  when detect_flask is called during zappa init, it fails on an encoding issue because of the commented out block at the head of xlrd/biffh.py
  <!--- Provide a more detailed introduction to the issue itself, and why you consider it to be a bug -->
  <!--- Also, please make sure that you are running Zappa _from a virtual environment_ and are using Python 2.7/3.6 -->
  
  ## Expected Behavior
  <!--- Tell us what should happen -->
  It should not error out.
  
  ## Actual Behavior
  <!--- Tell us what happens instead -->
  It fails with an encoding exception at f.readlines()
  
  ## Possible Fix
  <!--- Not obligatory, but suggest a fix or reason for the bug -->
  just add encoding='latin' to the open call
  
  ## 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. have xlrd as a dependency
  2. call zappa init
  3.
  
  ## Your Environment
  <!--- Include as many relevant details about the environment you experienced the bug in -->
  * Zappa version used:
  * Operating System and Python version: OSX, python 3
  * The output of `pip freeze`:
  * Link to your project (optional):
  * Your `zappa_settings.py`: 
  