Make AkCollator.getString() able to extract a printable / encodable string from a cached byte array.
Use this for formatting and hashing.
This makes case-insensitive BloomFilter cases that worked when CStringKeyCoder was used work when it is not.
It does not fix the cases that did not work, which not consistently and wrongly use the hex result of decodeSortKeyBytes(), either from CStringKeyCoder.decodeKeySegment() or from AkCollator.getString().
Use in MergeJoinSorter, too.
merge MMcM: Make AkCollator.getString() use collator's decode if it finds a byte array

Merge pull request #900 from MMcM/akiban-server/collator-more-getstring
https://github.com/FoundationDB/sql-layer/pull/900