Handle common issues on import

[slaporte]

When a coordinator imports files, Montage should:

• warn about deleted files Detect and resolve files deleted on Wikimedia Commons #30
• resolve moved files Automatically detect and resolve when a file is moved on Wikimedia Commons #97
• resolve full Wikimedia Commons URLs
• resolve URL encoding issues
• resolve common typos (spaces or underscores at the beginning or end of the filename)
• warn users when files are not imported Display any warnings and disqualifications after import #108
• save a log of files that were not imported Display any warnings and disqualifications after import #108
• provide an easy tool to figure out which files from your source list are not in the round Add coordinator panel to compare current round entries #140
• ensure there are no duplicate entry errors Importing duplicated files results in internal server error #146