Break apart data directories and installation directories.
Move data directory creation/permissions to be after package install as they may interact.
Move installation directory creation into the debian section.

Shouldn't break anything on the debian platform if it is required but it
can cause problems on rhel - especially if you've foolishly pointed
conf_dir at /etc/cassandra/conf which is where the package wants to put
a symlink.

Not sure why these are needed for packaged installs, but if they are, I
suspect at least some of them should be done after the package is
installed.

I've moved conf_dir down to ensure that it sets permissions
appropriately whether it is used by the package or not.
Make datastax.rb use the cassandra group attribute consistently.
Added resource to use the cassandra-rackdc.properties.erb template from
datastax recipe.

Previously only available from the tar install.
Added log4j-server.properties templating.

Was previously only available for tar installs.

Also added an attribute to configure the rootlogger property. Default is
the same as the RPM. Used to, for example, remove stdout logging.
Oops. double definition of conf_dir.
Merge pull request #97 from tjnicholas/templating_etc

Templating improvements and directory creation tweaks