GPII-884: Implement reading data from sensors within an Android platform

This is still a __first implementation__ of this feature and can be tested with [this KASPARNET's branch of universal] (https://github.com/kaspermarkus/universal/tree/GPII-795)

This pull requests adds the ability in the android implementation to report changes on the environmental data to the flow manager. Right now we're reporting changes about __luminosity__ and environmental __noise__ to the flow manager by making a __PUT__ request to _http://localhost:8081/environmentChanged_, and according to this [API contract](https://github.com/kaspermarkus/universal/blob/ccd58418529a6af8c126b887c0b0f10d15d6b1ce/documentation/ContextManager.md#reporting-changes-in-environment-put-environmentchanged)


This should be held as a member - HttpClient is documented as being threadsafe