Consistently describe composer as dep mgr as opposed to package mgr

Closes #1207.

README.md

@@ -1,7 +1,7 @@
 Composer - Package Management for PHP
 =====================================
 
-Composer is a package manager tracking local dependencies of your projects and libraries.
+Composer is a dependency manager tracking local dependencies of your projects and libraries.
 
 See [http://getcomposer.org/](http://getcomposer.org/) for more information and documentation.
 

composer.json

@@ -1,6 +1,6 @@
 {
     "name": "composer/composer",
-    "description": "Package Manager",
+    "description": "Dependency Manager",
     "keywords": ["package", "dependency", "autoload"],
     "homepage": "http://getcomposer.org/",
     "type": "library",

src/Composer/Command/AboutCommand.php

@@ -36,7 +36,7 @@ EOT
     {
         $output->writeln(<<<EOT
 <info>Composer - Package Management for PHP</info>
-<comment>Composer is a package manager tracking local dependencies of your projects and libraries.
+<comment>Composer is a dependency manager tracking local dependencies of your projects and libraries.
 See http://getcomposer.org/ for more information.</comment>
 EOT
         );

tests/Composer/Test/Package/Dumper/ArrayDumperTest.php

@@ -97,7 +97,7 @@ class ArrayDumperTest extends \PHPUnit_Framework_TestCase
             ),
             array(
                 'description',
-                'Package Manager'
+                'Dependency Manager'
             ),
             array(
                 'keywords',