Sending raw HttpEntities to Get or Delete request like for JSON payloads.

This is the implementation of HTTP GET and DELETE request calls synonymous to 
```
public RequestHandle post(Context context, String url, Header[] headers, HttpEntity entity, String contentType,
                              ResponseHandlerInterface responseHandler) {
}
```
It means to serve raw `HttpEntity` payloads to the get and delete requests if the queries can handle one.
Doing this will allow to pass `JSON`, etc. via the entities.

For the same new `HttpDelete` and `HttpGet` are added which extends `HttpEntityEnclosingRequestBase` to add the supplied entities to the request base.
This will help in sending our own `Content-Type` with the entities instead of `application/x-www-form-urlencoded`