Revert "Revert "Make CWM buildable and executable""

This reverts commit b667a8e8f61411af2f3d70bc77fb1c01390732f8.
Add BOARD_RECOVERY_CWM to check if we are building cwm

Change-Id: I8ae41f8c8428272769b4d2914c7c51bd6257ea6b
core/Makefile: update BOARD_CUSTOM_BOOTIMG_MK fix
this updates code left out from commit fd88ca3

Change-Id: I86ceb22001b92f1b631000d0cefa84a64d11370e
build: Fix usage of releasetool

Change-Id: I15766759195e86c0f9395cfce0b98c5a5a3f6f63
Build CellBroadcastReceiver

Change-Id: I8051b44c2e6775ebb4359c67f96e704f42d2f7dd
core: main: silence spamming about including make files

Change-Id: I103058259bc3e1f093d5c59921c74d194c0d8a38