Make template token objects adhere token object structure

While fixing an issue in `eslint-plugin-react`
(jsx-eslint/eslint-plugin-react#1061),
I noticed that template tokens differ from other tokens. A typical token
looks like this:

```
Token {
  type: 'String',
  value: '"bar"',
  start: 44,
  end: 49,
  loc:
   SourceLocation {
     start: Position { line: 4, column: 11 },
     end: Position { line: 4, column: 16 } },
  range: [ 44, 49 ] }
```

A template token looks like this:

```
{ type: 'Template',
  value: '`bar`',
  loc:
   { start: Position { line: 4, column: 11 },
     end: Position { line: 4, column: 16 } },
  range: [ 44, 49 ] }
```

I've not be able to figure out why templates are plain JavaScript
objects and not of the class type `Token` (aside from the fact that the
template tokens are constructed differently in the token translator.

This fix copies the `range` values into `start` and `end` properties on
the template tokens to make them adhere to the same structure as other
token objects.

Fixes eslint#319

lib/token-translator.js

@@ -58,6 +58,8 @@ function convertTemplatePart(tokens, code) {
 
     if (firstToken.range) {
         token.range = [firstToken.range[0], lastTemplateToken.range[1]];
+        token.start = firstToken.range[0];
+        token.end = lastTemplateToken.range[1];
     }
 
     return token;