AURORA-244: Fix zookeeper logs being swallowed due to missing log4j.properties

I ended up just using the default log4j properties file that comes
with Zookeeper. We might just want to write our own and use that in
the Vagrant image.

Testing Done:

In Vagrant:

sudo stop aurora-scheduler
sudo rm /var/log/upstart/aurora-scheduler.log
sudo start aurora-scheduler

No more message about a missing log4j appender.

Bugs closed: AURORA-244

Reviewed at https://reviews.apache.org/r/20249/
Move gradlew back to project root.

This fixes IntelliJ integration with the gradle wrapper.

Testing Done:
Opening the gradle build script in IntelliJ 13.1 Ultimate works
out-of-the-box without the need to use the idea target.

git clean -fdx
idea build.gradle

Reviewed at https://reviews.apache.org/r/20069/