Emmet extension for expansion and all other actions using the new apis

[ramya-rao-a]

For April Milestone:

Emmet features are now modularized in https://www.npmjs.com/%7Eemmetio
For example: https://github.com/emmetio/expand-abbreviation is a stand alone module for the Expand Abbreviation feature from emmet.

This issue is to track the below emmet features in a VSCode extension using the new APIs and is essentially emmet 2.0

• Get emmet expansions in auto-complete suggestion list
• Wrap with Abbreviation
• Remove Tag
• Update Tag
• Go to Matching Pair

For May Milestone

• Balance Inward
• Balance Outward
• Split/Join Tags
• Merge Lines
• Toggle Block Comment (html)
• Toggle Block Comment (stylesheet)
• Go to Next/Previous edit point
• Select Next/Previous item (html)
• Select Next/Previous item (stylesheet)

Deferred to next Milestone

• Increment/Decrement by n
• Update Image Size
• Evaluate Math Expression
• Reflect CSS Value

[ramya-rao-a]

Initial commit: https://github.com/ramya-rao-a/vscode-emmet