Fix issue #78

- Fix deadlock caused by ReRunUpdateQueryTask and UpdateQueryTask are waiting for each other due to the shared UpdateQueryTask and UpdateQueryTokenSource variable.
- Synchronize Update method
Fix issue #81

- Add upperbound sequence to the select statement that will get the list of the documents to be indexed.
- Create a test case to reproduce the issue #81
New fix for issue #81

- Instead of putting a upperbound for sequence number which could has a
side effect that sometime there could be less or no documents indexed,
we can just check if we have a new max sequence from the actual
documents that are indexed and use the new max sequence accordingly.
- Rename ViewsTest.TestViewUpdateWithLiveQuery to
ViewsTest.TestViewUpdateIndexWithLiveQuery and reduce the sleeping time.
Merge pull request #89 from couchbaselabs/fix-issue-78-and-81

Fix issue 78 and 81