Guess Metadata from HTML and Converted to reStructuredText

Guess metadata from HTML webpage and convert it to reStructuredText format. Currently the following metadata extraction (if available) is supported:

Usage:

Check guess metadata from HTML commit in html2rst repo for details of source code.

Tested on: Ubuntu Linux 16.04, Go 1.6.2.

References:

[1]	[Golang] HTML to reStructuredText

[2]	Online Taobao Item to reStructuredText Image on Google App Engine Go

[3]	[Golang] Create reStructuredText Metadata via text/template Package

[4]	[Golang] Extract Title, Image, and URL via goquery

[5]	Extract title and metadata from a reStructuredText document // homework prod.