Add web proxy configuration support for linux clients network probes

[zeb]

Notes:

• Linux Java clients affected: insight, editor, importer
• Windows/MacOS clients not affected (network availability detected via network interface)
• UpgradeCheck behaviour affected on all clients behind a proxy: failing to configure proxy settings will result in timeout on connection to http://upgrade.openmicroscopy.org.uk (and possibly skewed usage stats). Not adressed here.
• Client server compatibilty check kicks in before NetworkChecker - not sure whether this is the intended behaviour (should it be the other way around?)

[jburel]

@zeb: we are currently modifying the logging system to use logback instead of log4 see #1062, so I will avoid introducing now the logger in NetworkCheck class since that is the strategy in place in insight (library like slf4j did not exist at the time)
That could be reviewed when we have made the transition.

[jburel]

@zeb: since you edited the file, better to replace you're connecting by you are connecting to be in synch with the rest of our doc

[zeb]

@jburel done - see 7929509

[bpindelski]

Tried testing locally, but didn't really manage to get a timeout. The changes in code look ok and the Insight process is started with proxy settings (if the .sh file is modified). Looks ok to merge.

[joshmoore]

Created a follow ticket: https://trac.openmicroscopy.org.uk/ome/ticket/10815

Thanks, @zeb!

[zeb]

@joshmoore Thanks. Just wondering if this might be included into the dev_4_4 line?
@jburel If the anwser to the above is yes, wondering how to deal with f458c53 which made it into dev_4_4 but not into develop

[jburel]

@zeb, @joshmoore: The reason it did not make it to develop is that we will require Java 1.6 or higher. so the Java 1.5 specific code should be removed.