file_level_encryption
minor nits addressed.

rename getTableCompressionEncryption to getTableEncryptionOptions.
Can rename EncryptorCompressor to EncryptingCompressor.
in ESW.flush() buffer.position(buffer.position() - 4); should be buffer.position(buffer.position() - CommitLog.END_OF_SEGMENT_MARKER)
change CompressionParameters to not instantiate the compressor at ctor time, but only create on demand via CP.getCompressorInstance

refactor SegmentWriter to be an abstract class, rather than an interface, and move many
fields/shared code up into it.

pass mutation size down to SW.write as we already calculate it.

refactoring init'ing of SegmentWriters

refactored to not use mmap