Logging: log filename and file size

[GoogleCodeExporter]

For file-based endpoints it would be useful to log the filename along with file 
size.

Suggest we add file-metadata to existing logging by:
1. Using dedicated fields in the logevent-schema (add new fields)
2. Extract file-metadata from the MuleMessage (if present), thus removing the 
need for explicit configuration in a logtransformer

Original issue reported on code.google.com by hakan.dahl@gmail.com on 12 Sep 2013 at 9:05

[GoogleCodeExporter]

This issue was updated by revision r2094.

Made a first attempt, added extraction of (filename, fileSize) in 
DefaultEventLogger.
No change of log-schema, added metadata to extraInfo-map.

Original comment by hakan.dahl@gmail.com on 21 Oct 2013 at 1:50

[GoogleCodeExporter]

This issue was updated by revision r2095.

Reverting changes, extracting data in the DefaultEventLogger doesn't give 
enough precision - filename is logged for both inbound and outbound if present.

Suggest we add extraction using an expression configured on a specific 
log-transformer instead.

Original comment by hakan.dahl@gmail.com on 21 Oct 2013 at 2:26