find7-common: fix Android.mk filter

Change-Id: Ibab242d4dd49827348c1a034389db3bc6c09b712
find7-common: remove unused mkbootimg.mk

Change-Id: Iec978590607b220ee330a07563d1439e74ed0d9a
find7-common: add recovery fstab and init

 * universal layout (Find 7a / Find 7s)
 * non universal for now, means unified and non unified are seperated

Change-Id: I8092cc5f7e709dcfe5ac5baa779f720b58e1ead7
find7-common: add back init

 * for use in recovery

Change-Id: Iadefccdc33ab58147a830ff8ba9c60b62d7bf813