fixed: --render option crash

The fs package was used incorrectly with a promise function. Used
the fs-extra package instead.

Fixes #220

Author: agnivade

lib/tldr.js

@@ -1,7 +1,7 @@
 'use strict';
 
 const sample = require('lodash/sample');
-const fs = require('fs');
+const fs = require('fs-extra');
 const ms = require('ms');
 const ora = require('ora');
 const cache = require('./cache');

test/functional-test.sh

@@ -14,8 +14,7 @@ function tldr-render-pages {
   tldr --list-all
 }
 
-tldr --update && \
-  tldr-render-pages && \
+tldr --render $HOME/.tldr/cache/pages/common/ssh.md && \
+tldr --update && tldr-render-pages && \
 tldr --clear-cache && \
-tldr --update && \
-  tldr-render-pages
+tldr --update && tldr-render-pages