Get codebase ready for actually supporting versioning.

utils/pub/command_install.dart

Index: utils/pub/command_install.dart
diff --git a/utils/pub/command_install.dart b/utils/pub/command_install.dart
index 7161b26056a15c06ea737189bd8dc0e0e3940da0..a582e10dbaf595e1bd9180639930d4e4d89178c8 100644
--- a/utils/pub/command_install.dart
+++ b/utils/pub/command_install.dart
@@ -7,7 +7,7 @@ class InstallCommand extends PubCommand {
   String get description() => "install the current package's dependencies";
 
   void onRun() {
-    packagesDir.installDependencies().then((_) {
+    entrypoint.installDependencies().then((_) {
       print('Dependencies installed!');
     });
   }