Changes to composer.json.

* repository information so version information can be inferred from
  tags rather than set statically.
* phpunit as a dev requirement
* APC as a suggested package.

Change-Id: I3f5b07c716e7aa426484bd313af09801c6e3fde2

composer.json

@@ -1,6 +1,5 @@
 {
 	"name": "mediawiki/core",
-	"version": "1.21-alpha",
 	"description": "Free software wiki application developed by the Wikimedia Foundation and others",
 	"keywords": ["mediawiki", "wiki"],
 	"homepage": "https://www.mediawiki.org/",
@@ -11,6 +10,12 @@
 		}
 	],
 	"license": "GPL-2.0",
+	"repositories": [
+		{
+			"type": "vcs",
+			"url": "https://gerrit.wikimedia.org/r/p/mediawiki/core.git"
+		}
+	],
 	"support": {
 		"issues": "https://bugzilla.wikimedia.org/",
 		"irc": "irc://irc.freenode.net/mediawiki",
@@ -19,9 +24,13 @@
 	"require": {
 		"php": ">=5.3.2"
 	},
+	"require-dev": {
+		"phpunit/phpunit": "*"
+	},
 	"suggest": {
 		"ext-fileinfo": "*",
 		"ext-mbstring": "*",
-		"ext-wikidiff2": "*"
+		"ext-wikidiff2": "*",
+		"ext-apc": "*"
 	}
 }