Make OMERO.blitz compilation optional

[jmoore]

Currently the blitz/ build requires that slice2java be on the classpath. We should make a best effort to find that via PATH and perhaps ICE_HOME, but at some point we should just bail. Perhaps an option like quick is necessary:

  java omero noice quick install

Note: there's a similar problem with the Ice/*.ice definitions.

[jmoore]

It might also make sense to ask for the value of etc/local.properties/ice.home during <setup/>. If no value is given, then blitz can be skipped.

[jmoore]

r1327 adds ice.home and no.ice checks.

[jmoore]

Not using the "noice" target.

Instead, it is necessary to set no.ice=false in etc/local.properties to make blitz properly build, in which ice.home will be checked. We may eventually want ice.home to default to env.ICE_HOME.