Draft: Apache http+ranger bom

[koushikr]

• Initial set of changes for movement from OkHttpClient to Apache http client, involves creating a single instance of ApacheHttpClient in the hubClient and in the simpleClient respectively, with lifecycle managed with the hub's start and stop.
• The above helps keep the interfaces simple.
• Added an HttpClientUtils to support client creation and also an execute method, helps provide a common interface for execute and also doesn't hold onto deserialization cost when the response object is still open, gets bytes, closes response object and then does de-ser. (The hub's getNodeList and getServiceList is typically hundreds in size)
• Initial set of changes for ranger-bom, for modules using ranger to use a consistent version
• Respective pom.xml changes across modules
• Changed the respective tests, added changelog and have done version upgrades across poms for the new release.