Update pom.xml
Show messages about comasters / masters
Crash when showing copy with no file

The cause of the crash was it asking for the fileType of a file that doesn't exist.  That would be crazy.

Additionally, there was no check on the existence of the file when showing a thumbnail.  You can only show a thumbnail if there is a file to show!
Merge pull request #340 from nla/hr-nullcopy-fix

Crash when showing copy with no file
RFC 6266 style Content-Disposition headers

For better behaviour in web browsers we need to include 'attachment'
Merge pull request #342 from nla/hr-rfc-6266

RFC 6266 style Content-Disposition headers
Merge remote-tracking branch 'origin/master' into hr-cmstrs

* origin/master:
  RFC 6266 style Content-Disposition headers
  Crash when showing copy with no file
  Update pom.xml