Minor updates for the tools scripts:

* Add ONOS-specific directories to the executable PATH in the envDefaults file
* Fix a typo inside "onos-show-cell": don't show OC0, because it is not used
diff --git a/tools/build/envDefaults b/tools/build/envDefaults
index cbc6577..f1e1346 100644
--- a/tools/build/envDefaults
+++ b/tools/build/envDefaults
@@ -9,6 +9,10 @@
 export KARAF_TAR=${KARAF_TAR:-~/Downloads/apache-karaf-3.0.1.tar.gz}
 export KARAF_DIST=$(basename $KARAF_ZIP .zip)
+# Add ONOS-specific directories to the exectable PATH
+export PATH="$PATH:$ONOS_ROOT/tools/dev/bin:$ONOS_ROOT/tools/test/bin"
+export PATH="$PATH:$ONOS_ROOT/tools/build"
 # Fallback build number us derived from from the user name & time
 export BUILD_NUMBER=${BUILD_NUMBER:-$(id -un)~$(date +'%Y/%m/%d@%H:%M')}