v0.16.3

In this release:

• Link: Options for target=_blank and rel=nofollow (#372)
• Rename unsafe react lifecycle methods (#345)
• Feature/block level text align (#356)
• Some i18n support (button labels) (#295)
• Added option to render the toolbar on the bottom of the editor (#318)
• Closes #282: Improve React ref (#283)
• Allow editing links via the toolbar button (#276)
• Fix this._currentValue assignment variable order (#254)