Turn on all of Microsoft's recommend lint rules

Biggest changes forced by this: alt tags for all images, resulting in
new strings added to messages.json, and a new i18n paramter/prop added
in a plot of places.

Another change of note is that there are two new tslint.json files under
ts/test and ts/styleguide to relax our rules a bit there. This required
a change to our package.json script, as manually specifying the config
file there made it ignore our tslint.json files in subdirectories

ts/components/conversation/AddNewLines.tsx

@@ -8,7 +8,7 @@ interface Props {
   renderNonNewLine?: RenderTextCallback;
 }
 
-export class AddNewLines extends React.Component<Props, {}> {
+export class AddNewLines extends React.Component<Props> {
   public static defaultProps: Partial<Props> = {
     renderNonNewLine: ({ text, key }) => <span key={key}>{text}</span>,
   };