Adding a query with the same id as an old query should overwrite it

Updates weren't working properly here - the old version of the query was still
in the index and would still be run.
Merge branch 'master' of https://github.com/flaxsearch/luwak into issue8

Conflicts:
	src/test/java/uk/co/flax/luwak/TestMonitor.java
Mockto instead of real obiect in TestIntervalsMatches
Merge pull request #9 from prog8/issue8

Use mockito object instead of MatchAllDocsQuery to ensure that query throws an exception.