Source is using JDK7 items, when target is 1.6 [JIRA: CLIENTS-521] #527

Currently in the pom, the maven-compiler-plugin says the source and target are 1.6, however Eclipse complains about two usages of JDK7 code in the codebase:

• https://github.com/basho/riak-java-client/blob/develop/src/main/java/com/basho/riak/client/api/RiakClient.java#L265 - getHostString() is not visible
• https://github.com/basho/riak-java-client/blob/develop/src/test/java/com/basho/riak/client/core/fixture/NetworkTestFixture.java#L20 - java.net.StandardSocketOptions was introduced in JDK7

I guess we could fix this by either increasing the minimum version to 1.7 or find JDK6 equivalents.