JBIDE-13759 Reorganize Seam tests to avoid having too many tests plugins

Removed tests for Seam 2.0.x, 2.1.x, 2.2.0.x. So we now have tests for Seam 1.2.1.EAP, FP, 2.1.2.GA, 2.2.1.GA, 2.3.0.Final only.
JBIDE-13811 - SeamTest are failing with exception in setUp method

added catch block for IllegalStateException with logging. It means
code would not fail and lets tests to be continued

fixed the npe

ss
JBIDE-13452 remove Snapshots label on site; remove redundant configuration; move update.site.name up to properties list