[2.0] Removing upgrade file as it is not needed

UPGRADE_TO_2_0

-## Installing
-
-Currently the only way to install is via svn. So just checkout the trunk.
-
-    $ svn co http://svn.doctrine-project.org/trunk/lib doctrine
-    $ cd doctrine
-
-## Loading Doctrine
-
-First we need to require one class, the `ClassLoader`.
-
->**NOTE**
-> This assumes you've created some kind of script to test the following code in. Something like a `test.php` file.
-
-    [php]
-    // test.php
-
-    require_once 'lib/Doctrine/Common/ClassLoader.php';
-
-Now we need to instantiate the `ClassLoader` and register it:
-
-    [php]
-    $classLoader = new \Doctrine\Common\ClassLoader();
-    $classLoader->register();
-
-The Doctrine `ClassLoader` supports the ability to use it for loading other classes with a prefix.
-
-Here are the recommend usages for the Doctrine `ClassLoader`:
-
-* Use only 1 class loader instance.
-* Set the base paths to your class libraries (including Doctrine's) through
-
--
-
-    [php]
-    $classLoader->setBasePath($prefix, $basePath);
-
-For example you can set the path for Doctrine with the following:
-
-    [php]
-    $classLoader->setBasePath('Doctrine', '/usr/local/phplibs/doctrine/lib');
-
-Then, when trying to load the class Doctrine\ORM\EntityManager, for example the class loader will look for /usr/local/phplibs/doctrine/lib/Doctrine/ORM/EntityManager.php
-
-* DO NOT setCheckFileExists(true). Doing so is expensive in terms of performance.
-* Use an opcode-cache (i.e. APC) (STRONGLY RECOMMENDED).
-
-## Initialize Doctrine
-
-    [php]
-    $config = new \Doctrine\ORM\Configuration();
-    $config->setMetadataCacheImpl(new \Doctrine\ORM\Cache\ArrayCache);
-    $eventManager = new \Doctrine\Common\EventManager();
-    $connectionOptions = array(
-            'driver' => 'pdo_sqlite',
-            'path' => 'database.sqlite'
-    );
-    $em = \Doctrine\ORM\EntityManager::create($connectionOptions, 'doctrine', $config, $eventManager);
-
-## Getting the Connection
-
-    [php]
-    $conn = $em->getConnection();
-    $conn->delete('table_name', array(1, 3, 10));
-
-The DBAL Connection class has lots of useful functions. You can browse the code and check the API to get familiar.
-
-## The Schema Manager
-
-The schema manager is a nice API for issuing database DDL statements like creating a table, or dropping a table.
-
-    [php]
-    $sm = $connection->getSchemaManager();
-
-The schema manager allows you to do all the familiar options on your schema. Like `createTable()`. Below you will find an example:
-
-    [php]
-    $sm->createTable($tableName, $columns, $options);
-
-## The Platform Object
-
-The platform object is the object that provides the appropriate SQL to the schema manager for the DDL statements.
-
-    [php]
-    $platform = $connection->getDatabasePlatform();
-
-Now we can get the generated SQL instead of executing it directly:
-
-    [php]
-    $sql = $platform->getCreateTableSql($tableName, $columns, $options);
\ No newline at end of file