Clients logback config

This PR modifies two logging related settings for the OMERO desktop clients:
- reduces the size of log files being retained on the user's workstation from `10 * 500000KB` to `10 * 10MB`
- distinguishes filenames for Insight and Importer when running as standalone applications (ie. not applicable when Importer is launched from within Insight)

Some possible testing steps:
- check for the presence of `$HOME/omero/log/omeroimporter.log` and `$HOME/omero/log/omeroinsight.log` when launching Importer and Insight, respectively
- check for the presence of `$HOME/omero/log/omeroinsight.log` only when launching Importer from within Insight
- check for rotation in `$HOME/omero/log` with:
  * generate random candidates for rotation with:  `dd if=/dev/zero of=$HOME/omero/log/omeroimporter.log count=1 bs=20M` and  `dd if=/dev/zero of=$HOME/omero/log/omeroinsight.log count=1 bs=20M`
  * import a fake file with Importer and create a dummy Dataset with Insight