Alphabetizing PHP packages in README

Change-Id: Ie2fb6e6dc9fe1d9101bd75e85d634b84c3eb7cbe

README

@@ -38,21 +38,21 @@ Mahara 1.9 requires:
    extensions.
 
  * PHP 5.3 or later, with the following extensions:
+ ** curl
  ** gd (including Freetype support)
  ** json
- ** curl
  ** libxml
- ** SimpleXML
- ** session
- ** pgsql; or mysqli; or mysql
- ** openssl and xmlrpc (for networking support)
  ** mbstring
- ** mime_magic; or fileinfo
  ** mcrypt
+ ** mime_magic; or fileinfo
+ ** pgsql; or mysqli; or mysql
+ ** session
+ ** SimpleXML
+ ** bz2 (optional)
  ** imagick (optional)
- ** zlib (optional)
+ ** openssl and xmlrpc (optional; for networking support)
  ** zip (optional)
- ** bz2 (optional)
+ ** zlib (optional)
  ** ... and ensure that the magic_quotes and register_globals settings are off.
 
  * OS: Mahara is only officially supported on Debian (5.0/"Lenny" or later) and