Initial work on cleaning up com.hazelcast.client package
Fixed package naming issue in PortableHook
Checkstyle fixes
Moved transaction request package to com.hazelcast.transaction
Fixed checkstyle issue with ClientTxnportableHook
Minor checkstyle improvement
Fixed automatic renaming issue; requests -> client -> requests
Moved client.client to client.impl.client
Fixed compilation problem: someone checked in code that doesn't compile
Merge pull request #3218 from pveentjer/cleanup/3.x/core-client-impl

Cleanup/3.x/core client impl
setter should return MapConfig
Merge branch 'master' of https://github.com/hazelcast/hazelcast