[maven-release-plugin] prepare release v1.2.1
[maven-release-plugin] prepare for next development iteration
patch from AquaFold reviewed and integrated and README.md updates

- CurrentDirectoryHandler interface and DefaultCurrentDirectoryHandler implementation allowing an implementer to intercept and specially handle path resolution and cwd related operations
- minor refactoring of some parameter names
- options handling in Mongo adaptor class
- added horn-of-mongo google group links to README.md since github issues are not that effective for user-developer dialog on general project topics