Update PrimitiveConverter.php

Map can contain null values
XML converter test file

@todo needs more test files to validate XML conversions
Implemented logging.

Added class PsrLoggerBridge, which connects PSR3's LoggerInterfaces to
specified RestHttp's logging events.

Implemented FileLogger.
XmlConverter fixed building XML from array

- ampersand and left angle bracket are now properly escaped
- fixed building XML containing a single root element
- fixed nodes containing empty elements
Added more tests and example test files
Tests bootstrap-local

Phpunit bootstrap file for testing with local source files
Olap cube limit and offset

Limit and offset as optional arguments in all olap methods
Removed v3 and v5 UUIDs

UUIDs versions 3 and 5 were not used
Minor changes to version 4 generation
Fixed error when logging is enabled.

Fixed error in processing of Http request when logging is enabled and
request body is empty.
Merge remote-tracking branch 'upstream/master' into logging
Merge pull request #4 from rpetrano/logging

Implemented logging.
Merge branch 'master' of github.com:ngs-doo/dsl-client-php
Fixed logger typo

log=>Log in Requirements.php
Multiple find, history

Multiple find and history are PUT request
Tests config

client config in phpunit.xml
More cube tests
Fixed inavlid path to some logging components.
Enum concept

Enum values are strings implemented as constants in abstract class
Minor tests update
Namespace prefix

Optional namespace prefix in RestHttp client
Namespace prefix is appended to all generated classes
Removed Name class, naming methods moved to RestHttp
@todo should rename RestHttp => HttpClient
Merge remote-tracking branch 'upstream/master' into logging
Fixed logging when connection to app server has failed.