Added JAVADOC NOTICE about getting more notifications by implementing ClientE…

[ktogias]

Making this pull request after xor-freenet's prompt on IRC. This is about getting detailed progress notifications with ClientPutCallback.

Added the following text to the comment at top of the class:

• 
  
  
• NOTICE: This interface provides onGeneratedURI, onGeneratedMetadata, onFetchable, onSuccess
• and onFailure methods for getting notified about the progress of the insert process.
  
• If you want to get more detailed progress notifications you have to also implement {@link ClientEventListener}
• interface and subscribe your callback to the {@link ClientEventProducer} of the putter's
• {@link InsertContext} using event producer's addEventListener method.
  
• This way your callback will be able to receive the following events during the insert:
• {@link ExpectedHashesEvent}, {@link StartedCompressionEvent}, {@link FinishedCompressionEvent}
• and {@link SplitfileProgressEvent}.

[Bombe]

I would suggest to squash your last two commits so that the onSuccess/onFailure line is not touched at all.

[Thynix]

These commit messages do not meet the standards, but I'm willing to fix it for you if you like. I'll merge this once Bombe's points are addressed.

[Thynix]

@ktogias Ping.