There is another option you may wish to try—it's what I needed for one of my installs, and it required no additional modules:
First, in your .htaccess:
RewriteCond %{HTTPS} !on
RewriteCond %{HTTP_HOST} ^www\.yourdomainhere\.com*
RewriteRule ^(.*)$ https://www.yourdomainhere.com/ [L,R=301]
This should be added after:
RewriteEngine on
Then, in your settings.php:
$base_url = 'https://www.yourdomainhere.com';
Also, you may want to check for external resources, such as Web fonts and other references that need to be coming from an https domain in order to avoid certificate warnings.
Hope this helps.