Revert "Update POM version numbers to 5.0.0-rc2"

This reverts commit ceb3c487984ba48b210af85cfd97c65ed0f7a540.
Update last version number to 5.0.0-rc2
Fix updater menu item to match window title
merge dev_5_0 -D org -I include -E exclude: PR 903 (Fix upgrade checker to delete loci_tools.jar when appropriate)
merge dev_5_0 -D org -I include -E exclude: PR 905 (Revert "Update POM version numbers to 5.0.0-rc2")