Add a HTable get/obtainScanner method that retrieves all versions of a particular column and row between two timestamps

The use case:

• A weblog application for which rows are user ids and posts are stored in a single column, with post date specified by the cell's timestamp. The application would then need to be able to display all posts for the last week or month.
• A feedfetcher for which rows are URLs and feed posts are stored in a single column with the post publish date or fetch time stored in the cell's timestamp. The application would then need to be able to display all posts for the last week or month.

Proposed API:

// Get all versions of the specified row and column whose timestamps are in [minTimestamp, maxTimestamp]
SortedMap<long, byte[]> getTimestamps(Text row, Text column, long minTimestamp, long maxTimestamp);

// Get all versions of the specified row and column whose timestamps are >= minTimestamp
SortedMap<long, byte[]> getTimestamps(Text row, Text column, long minTimestamp);

I'd be happy to take this on myself, as I need it for the above use cases before migrating my application over to HBase.