Remove /boot/common for good

* Remove support for the "common" installation location from packagefs,
  package kit, package daemon, package managers.
* Rename the B_COMMON_*_DIRECTORY constants referring to writable
  directories to B_SYSTEM_*_DIRECTORY.
* Remove/adjust the use of various B_COMMON_*_DIRECTORY constants.
  I'm sure some occurrence still remain. They can be adjusted when the
  remaining B_COMMON_*_DIRECTORY constants are removed.

headers/os/package/PackageDefs.h

@@ -1,5 +1,5 @@
 /*
- * Copyright 2011, Haiku, Inc.
+ * Copyright 2011-2013, Haiku, Inc.
  * Distributed under the terms of the MIT License.
  */
 #ifndef _PACKAGE__PACKAGE_DEFS_H_
@@ -11,7 +11,6 @@ namespace BPackageKit {
 
 enum BPackageInstallationLocation {
 	B_PACKAGE_INSTALLATION_LOCATION_SYSTEM,
-	B_PACKAGE_INSTALLATION_LOCATION_COMMON,
 	B_PACKAGE_INSTALLATION_LOCATION_HOME,
 
 	B_PACKAGE_INSTALLATION_LOCATION_ENUM_COUNT