Use %(version)s in gbp.conf for debian branch

This way gbp.conf needs zero modifications on every new version

Change-Id: Ie3f0647b1fc629156c47de4bbd438151aaee5ed1
Fix typo with scalac/scala in b918cc9e2

scalac is the dependent binary, not the package name

Change-Id: Ifb2a41cc03e0cf022cb3fc2df8c0f32f614f7f17
Add package building instruction in the README

Change-Id: I46c3b4dcc244eb4e070fa28b51b4f71facf38580
Merge "Fix typo with scalac/scala in b918cc9e2" into debian
Check KAFKA_START before JAVA_HOME

Currently, if Java hasn't yet been set up when this package is installed,
installation will fail when the init script checks for JAVA_HOME.

Instead, check for KAFKA_START first---it will be 'no' immediately upon
installation---and abort cleanly before failing to find Java.

Change-Id: I6b38ac4e499647cb603356ee25829210a2624530
Check KAFKA_START before JAVA_HOME (kafka-mirror)

This applies the same change from bab68f62 to the kafka-mirror init
script.

Change-Id: I2165b372acfc49c6ee220ff9b43ad2b4876e04ed
Depend on any java7 jre/jdk
Use log4j-1.2 instead of log4j-1.2.16

/usr/share/java/log4j-1.2.jar is a symlink to the latest installed
log4j 1.2. This fixes an issue where we have log4j-1.2.17 but not 1.2.16.