Bug Fix Update

• Fixed IndexError caused by NSE updating the method they use for loading symbols on their website.
  Issue: #54, #55, #56
• No longer uses the web scraping technique to load symbols
  • Instead uses the API to load symbols as that is what the new NSE website uses
  • Removed beautifulsoup4 from requirements.txt as it is no longer required
• Updated documentation:
  • Removed beautifulsoup4 from dependencies