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.

Add BPackageRoster::GetActivePackages()

The implementation is temporary. Currently it reads through the packages
in the respective packages directory and checks against the package
links. Once package activation is tracked explicitly we'll use the
activation file/directory.

Add BPackageRoster::GetActivePackages()

The implementation is temporary. Currently it reads through the packages
in the respective packages directory and checks against the package
links. Once package activation is tracked explicitly we'll use the
activation file/directory.

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.

Add BPackageRoster::GetActivePackages()

The implementation is temporary. Currently it reads through the packages
in the respective packages directory and checks against the package
links. Once package activation is tracked explicitly we'll use the
activation file/directory.

Add BPackageRoster::GetActivePackages()

The implementation is temporary. Currently it reads through the packages
in the respective packages directory and checks against the package
links. Once package activation is tracked explicitly we'll use the
activation file/directory.