Update sbt to 0.14.5

Also install bc as it is now required by sbt

Step 3/8 : RUN cd /tmp && echo hello | sbt new sbt/scala-seed.g8
 ---> Running in 0262ba9e571e
/usr/share/sbt/bin/sbt-launch-lib.bash: line 207: bc: command not found

Also update sbt to 0.14.5, as it's failing with:

[error] sbt.librarymanagement.ResolveException: unresolved dependency:
com.eed3si9n#sbt-assembly;0.14.4: not found

Reason why it fails is because we will be using scala version 2.12,
that only has 0.14.5+

See https://dl.bintray.com/sbt/sbt-plugin-releases/com.eed3si9n/sbt-assembly/scala_2.12/

in ubuntu 15.04 it was using scala bersion 2.10 which had 0.14.4.

Change-Id: Ib051dd347eaea2c77ae6c403ebf76bed4b9b4b9c
diff --git a/jenkins-docker/slave-sbt/Dockerfile b/jenkins-docker/slave-sbt/Dockerfile
index 3ee9fcd..cdc6d09 100644
--- a/jenkins-docker/slave-sbt/Dockerfile
+++ b/jenkins-docker/slave-sbt/Dockerfile
@@ -2,7 +2,7 @@
 
 # SBT Setup
 RUN apt-get update && \
-    apt-get -y install apt-transport-https && \
+    apt-get -y install bc apt-transport-https && \
     echo "deb https://dl.bintray.com/sbt/debian /" | tee -a /etc/apt/sources.list.d/sbt.list && \
     apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv 642AC823 && \
     apt-get update && \
@@ -12,7 +12,7 @@
 
 # SBT warm-up
 RUN cd /tmp && echo hello | sbt new sbt/scala-seed.g8
-RUN echo 'addSbtPlugin("com.eed3si9n" % "sbt-assembly" % "0.14.4")' >> /tmp/hello/project/plugins.sbt
+RUN echo 'addSbtPlugin("com.eed3si9n" % "sbt-assembly" % "0.14.5")' >> /tmp/hello/project/plugins.sbt
 RUN chown -R jenkins: /tmp/hello
 
 USER jenkins