improve crypto perf
Requesting chunkchecksums in batches for performance
Fixing up UploadInterrupted test (was still dependent on system load and such)
Using BC implementation directly; to avoid the use of the broken CipherInputStream
Added fixed BC CipherInputStream; still two tests failing
Fixed crypto issues with Cipher*Stream
Merge branch 'performance-chunkchecksum-batch' of https://github.com/pimotte/syncany