SOLR-4796: zkcli.sh should honor JAVA_HOME (backported from branch_4x)

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/lucene_solr_4_3@1483666 13f79535-47bb-0310-9956-ffa450edef68
SOLR-4734: Leader election fails with an NPE if there is no UpdateLog (backported from branch_4x)

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/lucene_solr_4_3@1483669 13f79535-47bb-0310-9956-ffa450edef68