oscam: Add oscam

Source:
https://github.com/tobiaswaldvogel/openwrt-addpack/blob/631dd741d0b537cf60b96ae4fc6988d15a836c12/oscam/Makefile
lua-zlib: Add lua-zlib

Notes:
This package is required for prosodys mod_compression.
http://prosody.im/doc/modules/mod_compression