Update requirements section

INSTALL

@@ -11,10 +11,11 @@ REQUIREMENTS
 
 * The Apache, Lighttpd, Cherokee or Hiawatha web server
 * .htaccess support allowing overrides for DirectoryIndex
-* PHP Version 5.3.7 or greater including
+* PHP Version 5.3.7 or greater including:
    - PCRE, DOM, JSON, Session, Sockets, OpenSSL, Mbstring (required)
-   - PHP Data Objects (PDO) with driver for either MySQL, PostgreSQL or SQLite (required)
-   - Libiconv, Zip, Fileinfo (recommended)
+   - PHP PDO with driver for either MySQL, PostgreSQL, SQL Server, Oracle or SQLite (required)
+   - Libiconv, Zip, Fileinfo, Intl, Exif (recommended)
+   - LDAP for LDAP addressbook support (optional)
 * PEAR packages distributed with Roundcube or external:
    - Mail_Mime 1.10.0 or newer
    - Net_SMTP 1.7.1 or newer
@@ -33,9 +34,8 @@ REQUIREMENTS
    - magic_quotes_runtime disabled
    - magic_quotes_sybase disabled
    - register_globals disabled (PHP < 5.4)
-* PHP compiled with OpenSSL to use secure (tls/ssl) connections and to use the spell checker
-* A MySQL (4.0.8 or newer), PostgreSQL, MS SQL Server (2005 or newer) database engine
-  or SQLite support in PHP
+* A MySQL (4.0.8 or newer), PostgreSQL, MS SQL Server (2005 or newer), Oracle
+  database or SQLite support in PHP
 * One of the above databases with permission to create tables
 * An SMTP server (recommended) or PHP configured for mail delivery
 * Composer installed either locally or globally (https://getcomposer.org)