On server startup, environment should be logged

ZooKeeper does a nice job of this, as evidenced in the Flume master startup logs. It would be nice to have the same info for Flume logged, especially the version number and class path. Will prove useful when we want to debug user logs as well.

10/07/27 15:50:06 INFO server.ZooKeeperServer: Server environment:zookeeper.version=3.3.0--1, built on 04/20/2010 18:49 GMT
10/07/27 15:50:06 INFO server.ZooKeeperServer: Server environment:host.name=10.0.0.122
10/07/27 15:50:06 INFO server.ZooKeeperServer: Server environment:java.version=1.6.0_17
10/07/27 15:50:06 INFO server.ZooKeeperServer: Server environment:java.vendor=Apple Inc.
10/07/27 15:50:06 INFO server.ZooKeeperServer: Server environment:java.home=/System/Library/Frameworks/JavaVM.framework/Versions/1.6.0/Home
10/07/27 15:50:06 INFO server.ZooKeeperServer: Server environment:java.class.path=/etc/flume/conf/:/usr/lib/hadoop/:./libtest/mockito-all-1.8.1.jar:./libtest/junit-4.8.1.jar:./lib/zookeeper-3.3.2-dev.jar:./lib/slf4j-simple-1.5.8.jar:./lib/slf4j-api-1.5.8.jar:./lib/servlet-api.jar:./lib/paranamer-2.1.jar:./lib/log4j-1.2.15.jar:./lib/libthrift.jar:./lib/jsp-api.jar:./lib/jline-0.9.94.jar:./lib/jetty-5.1.4.jar:./lib/jasper-runtime.jar:./lib/jasper-compiler.jar:./lib/jackson-mapper-asl-1.4.0.jar:./lib/jackson-core-asl-1.4.0.jar:./lib/ivy-2.1.0.jar:./lib/irclib.jar:./lib/hadoop-0.20.1+133-core.jar:./lib/google-collect-1.0-rc2.jar:./lib/flume-httpPostSink.jar:./lib/commons-logging-1.0.4.jar:./lib/commons-lang-2.4.jar:./lib/commons-io-1.2.jar:./lib/commons-el.jar:./lib/commons-cli-1.1.jar:./lib/avro-1.3.0.jar:./lib/automaton.jar:./lib/antlr-3.1.3.jar::/System/Library/Frameworks/JavaVM.framework/Versions/1.6.0/Home/lib/tools.jar:/usr/lib/zookeeper/:./build/flume-0.9.1-dev-core.jar:./*
10/07/27 15:50:06 INFO server.ZooKeeperServer: Server environment:java.library.path=./lib
10/07/27 15:50:06 INFO server.ZooKeeperServer: Server environment:java.io.tmpdir=/var/folders/3N/3NiEf4BHH3Ch5HLNJszezk+++TI/Tmp/
10/07/27 15:50:06 INFO server.ZooKeeperServer: Server environment:java.compiler=<NA>
10/07/27 15:50:06 INFO server.ZooKeeperServer: Server environment:os.name=Mac OS X
10/07/27 15:50:06 INFO server.ZooKeeperServer: Server environment:os.arch=x86_64
10/07/27 15:50:06 INFO server.ZooKeeperServer: Server environment:os.version=10.5.8
10/07/27 15:50:06 INFO server.ZooKeeperServer: Server environment:user.name=hammer
10/07/27 15:50:06 INFO server.ZooKeeperServer: Server environment:user.home=/Users/hammer
10/07/27 15:50:06 INFO server.ZooKeeperServer: Server environment:user.dir=/Users/hammer/codebox/flume-github