umurmur: Use example config and add own init script

umurmur: Use example config and add own init script

Files such as config file and init script related to OpenWrt
were removed in upstream [1]. Config file was same as umurmur.conf.example,
thus use it and init script, we need to ship our own. Add a simple one.

[1] https://github.com/umurmur/umurmur/commit/209edb5c887e5a5d3ab2c95ab4a8aeb8c1e6e8f3

Signed-off-by: Josef Schlehofer <[email protected]>