LEAD-196 implement getChannel() in ACassandraRandomAccessFile.
LEAD-196 changed log level to error and so we know when it is called.
LEAD-196 change FileDescriptor to reference org.apache.lucene.cassandra.FileDescriptor
LEAD-196 added to ctor and one reference by ACassandraRandomAccessFile.getChannel(). determined which method we must implement as this is called from project elasticsearchOnCassandra.
LEAD-196 ACassandraRandomAccessFile implement interface RandomAccessFile and this has to be changed.
LEAD-196 when random access file is close, close the channel as well.