rrepair, trivial: fix compress_key/2 not using a randomly distributed key
rrepair, trivial: fix compress_key/2 not using a randomly distributed key

By using erlang:term_to_binary/1 only, several bytes of the binary key representation were equal but we need randomly distributed keys in order to cut off arbitrary bits!
-> hash the binary representation with erlang:md5/1 before selecting bits
caijieming-baidu/scalaris,scalaris-team/scalaris,scalaris-team/scalaris,jvf/scalaris,scalaris-team/scalaris,jvf/scalaris,jvf/scalaris,scalaris-team/scalaris,scalaris-team/scalaris,caijieming-baidu/scalaris,jvf/scalaris,caijieming-baidu/scalaris,jvf/scalaris,caijieming-baidu/scalaris,caijieming-baidu/scalaris,scalaris-team/scalaris,jvf/scalaris,scalaris-team/scalaris,scalaris-team/scalaris,caijieming-baidu/scalaris,caijieming-baidu/scalaris,jvf/scalaris