Add support for reading email attachement and adding attachement to a mail in javamail (imap) implentation.

Hello,

I have added those functionalities (see title) for my own needs. Feel free to merge that piece of code in the main branches if interested.

I have done the changes you suggested. It should be ok now.
- Change tab characters into 4 spaces.
- Change if( to if (.
- Change for( to for (.
- Not Swallowing exception anymore. log.warn added.
- Remove unnecessary logging.

See you.