Add the ability to get Row cells in serverside order

[igorbernstein2]

Bigtable stores data in the following order:

1. lexicographically by row key
2. family creation order
3. lexicographically by qualifier
4. reverse chronological by timestamp

The family ordering is not guaranteed so the data client currently pre-processes each row to change the ordering of families to be lexicographic order. This makes it convenient to do binary searches for specific values.

Unfortunately, this has negative repercussions when combined with cells_per_row_limit_filter and cells_per_row_offset_filter. Those filters are executed on the server side using the family creation order.

At the very least we need to update our docs to caution users against using those filters outside of a chain that narrows it to a single family.

In addition we should expose the server ordering of the cells on each row as Row#getRawCells() (maybe with a better name).