Closing buffers when closing appender and tailer

Hi.
Noticed that some file handles were left open after closing the appender, tailer and chronicle.
Not sure this is the best way to fix it but with this change all file handles are closed. 
```java
		IndexedChronicle ic = new IndexedChronicle("ictest");
		ExcerptAppender a = ic.createAppender();
		ExcerptTailer t = ic.createTailer();

		ic.close(); t.close(); a.close(); // file handle still shows up in `lsof`
```