Also, the change in insert-hyperlink (from `this.linkUrl.indexOf("http") === -1` to `!this.linkUrl.startsWith("http")`) was intentional fix: we don't want to prevent users from looking up topics with http in their titles.
When editing the files for a theme in the admin dashboard, typing "cmd+s" (a common key-binding to save in most text editors) used to engage the browser's default "save page" dialogue.
This commit adds a key-binding to the ace editor that saves the file.
Now, the "cmd+s" (and "ctrl+s" for windows) key-binding does the same action as the save button.
