Update cassandra.init.erb
Update cassandra.init.erb


1) Added check for C* binary
2) Added check for nodetool binary
3) Added extra pre-steps for C* service stop:
   - disable thrift
   - disable gossip
   - node drain
TD-4242/cassandra-chef-cookbook,alrf/cassandra-cookbook,criteo-forks/cassandra-chef-cookbook,adityagodbole/cassandra-chef-cookbook,jfwm2/cassandra-chef-cookbook,msilvey/cassandra-chef-cookbook,michaelklishin/cassandra-chef-cookbook,vkhatri/cassandra-chef-cookbook,msilvey/cassandra-chef-cookbook,criteo-forks/cassandra-chef-cookbook,jfwm2/cassandra-chef-cookbook,alrf/cassandra-cookbook,TD-4242/cassandra-chef-cookbook,msilvey/cassandra-chef-cookbook,michaelklishin/cassandra-chef-cookbook,vdemonchy/cassandra-chef-cookbook,vkhatri/cassandra-chef-cookbook,adityagodbole/cassandra-chef-cookbook,jfwm2/cassandra-chef-cookbook,vkhatri/cassandra-chef-cookbook,vdemonchy/cassandra-chef-cookbook,alrf/cassandra-cookbook,vdemonchy/cassandra-chef-cookbook,michaelklishin/cassandra-chef-cookbook,TD-4242/cassandra-chef-cookbook,adityagodbole/cassandra-chef-cookbook,criteo-forks/cassandra-chef-cookbook