Improve API around basic authorization
Add integration tests for basic authorization
Unescape credentials on URI before adding basic auth header (ty @Tasteful)
Merge branch 'develop' into feature/basicauth

Conflicts:
	src/Elasticsearch.Net/Connection/Configuration/ConnectionConfiguration.cs
	src/Elasticsearch.Net/Connection/Configuration/IRequestConfiguration.cs
	src/Elasticsearch.Net/Connection/Configuration/RequestConfiguration.cs
	src/Elasticsearch.Net/Connection/Configuration/RequestConfigurationDescriptor.cs
	src/Elasticsearch.Net/Connection/HttpConnection.cs