Update a website via Gwen

[tysloan]

Description: This story is part of getting to a simple Level 1 customer usage of dweb hosting on Manifest. This story is to enable users to update their site via Gwen. This should be able to be achieved by dropping a ZIP file of the entire site and letting us unzip and deploy it. This is related to #91.

As a user, I want to update my site via Gwen so that it is current.

• Should be achievable via a UI (Gwen).
• Should be able to drag and drop or upload a zip file via the UI.
• Should be able to input the site's domain.
• Should be able to unzip and serve the website on Manifest.
• Should retain the SSL for the site.
• Should present an error message ("An error occurred.") to the user (in UI) if the site cannot be served.
• Should create documentation guide.
• Should be demoed.