Minor readme tweak
Add unit test to detect issue #164. Also enhance test to use public API.

https://github.com/couchbase/couchbase-lite-android/issues/164
add testDocumentCache() in attempt to repro issue #164, but in this case it did not detect any issues.
temporarily remove document cache from Database

The minimal set of changes required to remove the document cache from
the Database class. It's ugly, but it should be temporary (until the
cache is invalidated everywhere it needs to be).

See couchbase/couchbase-lite-android#164.
Revert "temporarily remove document cache from Database"

This reverts commit f1f8b94ecf9d1d1aa84fa1395927b746eca02b44.
Fix the issue detected in test case added in commit 68bd39a.  There were TODO's in the code that had not been ported over from iOS. Related to issue #164.

https://github.com/couchbase/couchbase-lite-android/issues/164
Test that reproduces issue in forceInsert where it was not sending out a change notification with the correct conflict state.

Noticed this issue while looking at the forceInsert method and seeing TODO's in the code.
Test that fixes issue in forceInsert where it was not sending out a change notification with the correct conflict state.

Unit test in previous commit now passes.
Write test that reproduces issue #24.  Also rewrite test to run faster and be simpler.  Minor change to ChangeTracker to support being inspected by test.

https://github.com/couchbase/couchbase-lite-android-core/issues/24
Fix for issue #24.  Unit test added in last commit now passes.

https://github.com/couchbase/couchbase-lite-android-core/issues/24