[SPARK-7913] [CORE] Increase the maximum capacity of PartitionedPairBuffe,...

[SPARK-7913] [CORE] Increase the maximum capacity of PartitionedPairBuffe, PartitionedSerializedPairBuffer and AppendOnlyMap

The previous growing strategy is alway doubling the capacity.

This PR adjusts the growing strategy: doubling the capacity but if overflow, use the maximum capacity as the new capacity. It increases the maximum capacity of PartitionedPairBuffer from `2 ^ 29` to `2 ^ 30 - 1`, the maximum capacity of PartitionedSerializedPairBuffer from `2 ^ 28` to `(2 ^ 29) - 1`, and the maximum capacity of AppendOnlyMap from `0.7 * (2 ^ 29)` to `(2 ^ 29)`.

Author: zsxwing <zsxwing@gmail.com>

Closes #6456 from zsxwing/SPARK-7913 and squashes the following commits:

abcb932 [zsxwing] Address comments
e30b61b [zsxwing] Increase the maximum capacity of AppendOnlyMap
05b6420 [zsxwing] Update the exception message
64fe227 [zsxwing] Increase the maximum capacity of PartitionedPairBuffer and PartitionedSerializedPairBuffer