LUN-1188: file title now available
* file title will hold some human readable "name" of an asset
* the current name field acts like a file name
* validation for file name without extension is now available
* validation error added to check if users sets unsupported
extensions in the file name field
LUN-1188: new tests for file name validation
* there is no need to access the actual file if the file is
already saved in the DB; this fix will make less IOErrors for
filer files that have corrupted files or don't have a file at all
Merge pull request #33 from pbs/LUN-1188

LUN-1188: file title now available