Improve metadata coverage, expose loadHTML method, deprecate support for node 0.10 & 0.12

This change deprecates support for node 0.10 and .12 and is compatible with 4, 6, & 8. It also updates packages to their latest versions.

The following improvements to the metadata scraping were made:

• Adds in PRISM metadata method parsePrism
• Adds in icon and apple touch icon metadata to the parseGeneral method
• Adds in xml lang attribute in the parseGeneral method if the html lang property is not available

Additional, a loadHTML method was exposed for scraping downloaded HTML files.

Fix warns and reject Errors instead of strings

• Fix warns
• Clean up tests & replace url that was timing out
• Rejection values return Errors instead of strings

Adds support for JSON-LD in script tags

Adds support for JSON-LD in script tags

Adds support for Twitter cards

Adds support for Twitter cards.