Enable eslint import checks and fixed the reported errors (#878)

Summary:
Pull Request resolved: https://github.com/facebook/flipper/pull/878

1) Enabled eslint error reporting for unresolved imports and fixed all the errors
2) Enabled eslint for typings (d.ts) and fixed all the errors

Reviewed By: passy

Differential Revision: D20335151

fbshipit-source-id: 7b142281a406b32df0f02a5cd0d7d05eba941acd

desktop/types/ansi-to-html.d.ts

@@ -8,7 +8,7 @@
  */
 
 declare module 'ansi-to-html' {
-    export default class Filter {
-      toHtml: (input: string) => string;
-    }
+  export default class Filter {
+    toHtml: (input: string) => string;
+  }
 }