Added an alternative section for installing Composer manually

_includes/dependency-management.md

@@ -10,12 +10,32 @@ There are already a lot of PHP libraries that are compatible with Composer, read
 
 ### How to Install Composer
 
-You can install Composer locally (in your current working directory) or globally (e.g. /usr/local/bin). Let's assume you want to install Composer locally. From your project's root directory:
+You can install Composer locally (in your current working directory; though this is no longer recommended) or globally (e.g. /usr/local/bin). Let's assume you want to install Composer locally. From your project's root directory:
 
     > curl -s http://getcomposer.org/installer | php
 
 This will download `composer.phar` (a PHP binary archive). You can run this with `php` to manage your project dependencies. <strong>Please Note:</strong> If you pipe downloaded code directly into an interpreter, please read the code online first to confirm it is safe.
 
+### How to Install Composer (manually)
+
+Manually installing composer is an advanced technique; however, there are various reasons why a developer might prefer this method vs. using the interactive installation routine. The interactive installation checks your PHP installation to ensure that:
+
+- a sufficient version of PHP is being used
+- `.phar` files can be executed correctly
+- certain directory permissions are sufficient
+- certain problematic extensions are not loaded
+- certain `php.ini` settings are set
+
+Since a manual installation performs none of these checks, you have to decide whether the trade-off is worth it for you. As such, below is how to obtain Composer manually:
+
+    > curl -s http://getcomposer.org/composer.phar -o $HOME/local/bin/composer ; chmod +x $HOME/local/bin/composer
+
+`$HOME/local/bin` (or a directory of your choice) should be in your `$PATH` environment variable. This will result in a `composer` command being available.
+
+When you come across documentation that states to run Composer as `php composer.phar install`, you can substitute that with:
+
+    > composer install
+
 ### How to Define and Install Dependencies
 
 First, create a `composer.json` file in the same directory as `composer.phar`. Here's an example that lists [Twig][2] as a project dependency.