Implements #710. Adding new unit tests.
Conflicts:
	src/main/java/com/jaeksoft/searchlib/Client.java
	src/main/java/com/jaeksoft/searchlib/index/IndexLucene.java
	src/main/java/com/jaeksoft/searchlib/index/WriterInterface.java
	src/main/java/com/jaeksoft/searchlib/index/WriterLocal.java
	src/main/java/com/jaeksoft/searchlib/webservice/query/document/DocumentsImpl.java