Issue #7: Add Tomcat Native Libraries

[ahromis]

Seems to work for every version of Tomcat and JRE in this repo -- seeing output like this when Tomcat starts:

Nov 17, 2015 5:46:38 PM org.apache.catalina.core.AprLifecycleListener lifecycleEvent
INFO: Loaded APR based Apache Tomcat Native library 1.1.33 using APR version 1.5.1.
Nov 17, 2015 5:46:38 PM org.apache.catalina.core.AprLifecycleListener lifecycleEvent
INFO: APR capabilities: IPv6 [true], sendfile [true], accept filters [false], random [true].
Nov 17, 2015 5:46:38 PM org.apache.catalina.core.AprLifecycleListener initializeSSL
INFO: OpenSSL successfully initialized (OpenSSL 1.0.1k 8 Jan 2015)

[md5]

LGTM

The Travis failure looks like a hiccup from a Debian mirror. Perhaps @tianon, @yosifkit, or @Moghedrin can rerun that build from the Travis site.

[andyshinn]

Related to #18, the URLs should be updated to https://archive.apache.org/dist/tomcat/tomcat-$TOMCAT_MAJOR/v$TOMCAT_VERSION/bin/apache-tomcat-$TOMCAT_VERSION.tar.gz as the main URL only has the latest version.

I pushed a Tomcat 7 JRE 7 image to andyshinn/tomcat:7-jre7 if anyone wants to test. It appears to be working for me (an application load and the APR warning is gone). However, I haven't yet done any performance testing to validate if things are actually faster with APR or not.

[yosifkit]

Could you sort the list and put it in a variable so it is easier to purge later? It should make it more obvious that libapr1 is not a build dependency, but a run dependency. Redis has a pretty similar example: https://github.com/docker-library/redis/blob/98a586a0f5c505e120b22dc94efc1fa5c492ce35/3.0/Dockerfile#L24-L36. You should also drop openssl since it is already in the java base image since it has curl.