fixes bug 977218 - Crontabber app to unpack the uploaded symbols archives

@twobraids @luser r?

What it does is it simply...
1. loops over all files in a source directory
2. For each file, unpack it into a destination directory...
    1. ...makes a new directory there which is the name of the file
    2. ...minus the extension
    3. ...plus todays date (e.g. `myfile.zip` becomes `myfile-20140321/`)
    4. ...and if there are multiple files that day with the same base, it comes `myfile-20140321-2`
3. Deletes the archive file if and only if the unpacking works
4. Other possible junk in the source directory (e.g. `README.txt`) gets ignored and logged as a warning

@luser, please say if it's a good or bad idea to unpack the archive files into additional sub-directories or whether it should just unpack right into the "root".