[package] option to allow boot to run to completion before starting shell

[package] option to allow boot to run to completion before starting shell

Setting the system variable "foreground" to yes causes the system to run
the init scripts in series and wait for completion.

This is useful if (a) you don't want the user getting into the console
until the system is initialized, or (b) you have things going on in your
scripts that require strict ordering (and no possible race conditions).

Signed-off-by: Philip Prindeville <philipp@redfish-solutions.com>
git-svn-id: svn://svn.openwrt.org/openwrt/trunk@20841 3c298f89-4303-0410-b956-a3cf2f4a3e73