Case sensitive property name configuration

[jnus]

Changed default mapping of property names to case sensitive. Can be configured in ElasticsearchSerializerConfiguration ctor to enable lower case stategy on all property names. Implementation is as non-invasive as possible with the use of an extension method.

Example: configure lower case strategy

            return new ElasticsearchContext(
                                "http://localhost:9200/",
                                new ElasticsearchSerializerConfiguration(
                                                        CreateMappingResolver(date),
                                                        saveChildObjectsAsWellAsParent:true,
                                                        processChildDocumentsAsSeparateChildIndex:false,
                                                        userDefinedRouting:false,
                                                        mapToLowerCase:true)
                );

Example: configure case sensitive strategy (default)

            return new ElasticsearchContext(
                                "http://localhost:9200/",
                                new ElasticsearchSerializerConfiguration(
                                                        CreateMappingResolver(date))
                );

[damienbod]

Hi Jasper, I am testing the pull branch and have noticed that the branch has a build problem and also that the Integration tests do not run because Elasticsearch indices have to be lowercase.

Greetings Damien