Use standard config locations

Use the standard config locations for zookeeper configuration
(/etc/zookeeper/conf) and state (/var/lib/zookeeper). This should make
it easier for users to work with our package. Since the package is
explicitly set to conflict with zookeeper and zookeeper-server, users
should be somewhat protected from having conflicting packages installed
at the same time.
Add PHONY's to phony targets
Merge pull request #2 from mesosphere/standard-config-locations

Use standard config locations