Feature Added: Word Count and Time To Read

[nataliepjlin]

Add word count features to address issue #379

Example outcome:

Usage:

1. Install hexo-word-counter

npm install hexo-word-counter
hexo clean

2. Add

symbols_count_time:
  symbols: true
  time: true
  total_symbols: false
  total_time: false
  exclude_codeblock: true
  wpm: 275
  suffix: " mins."

to Hexo's _config.yml in the root dir of the blog. See more configuration in https://github.com/next-theme/hexo-word-counter.