fix NPE thrown on getAll requests with single key
Incorporating code review comments for changes in R2Store
Move to tusk-0.0.2 version
Update build.properties and release_notes for version 1.6.9
Adding BDB5 instructions
Refactor schema backward compatibility check

1. Fix a bug that will leave a store created even when exception has been thrown
2. Consolidate strings used by tests
3. Consolidate backward compatiblity check into StoreDefinitionUtils
Changed setReadOnly(true) -> setReadOnly(false) to prevent writing file summary fail when during bdb conversion
Merge pull request #169 from jameswu0629/bdb-conversion-0.9x-1.6.x

Changed setReadOnly(true) -> setReadOnly(false) to prevent writing file summary fail when during bdb5 conversion