Img meta data - strips alignment from html

[meremagee]

Currently, if you edit the img meta data of a post drafted on wp-admin, we reset the alignment. We should preserve alignment/update the meta details page with alignment in the original html.

repro:

• add image in wp-admin web
• inline, change alignment (by clicking image then using contextual menu)
• publish post
• open post on ios app
• tap edit
• go to html mode -- notice alignment specs in img class
• go to visual mode
• tap image to edit meta data
• notice that align is set to "none"
• close
• go to html
• alignment info is wiped from html

[aforcier]

This may be fixed by importing the changes made to the ZSSEditor Android-side in this commit.

Backstory: https://github.com/wordpress-mobile/WordPress-Editor-Android/pull/244#issuecomment-138863969

[bummytime]

:+1: