Implement Filesystem based ActiveRecord

[kefahi]

Pretty much like Redis ActiveRecord except that this ActiveRecord will use File systme api instead of Redis Api.

The key is the entry path: say notes/study/english/grammer.json
and the content (data) of the entry is json for now (later we can extend this to bson and xml if needed).

It should be possible to access (read/write) the json entries as an object. PHP Serialized object could be used for now instead of json to make it simpler to read/access/write.

This will become the heart of the new system. We could later on think of using a query capability (for example index via clucene.