construct a default entry for local site if not present in site catalog

users keep on tripping over missing site catalog entry for local site and planner throws a NPE

example snippet from trace by pavlo

[tutorial@98e2582be563 test]$ ./plan_cluster_dax.sh split.dax
2018.12.10 19:48:36.048 UTC: [ERROR] **Parsing ** Line: 12
[org.xml.sax.SAXParseException; lineNumber: 12; columnNumber: 70; cvc-complex-type.2.4.a: Invalid content was found starting with element 'directory'. One of '{"http://pegasus.isi.edu/schema/sitecatalog":profile, "http://pegasus.isi.edu/schema/sitecatalog":metadata}' is expected.]

2018.12.10 19:48:36.064 UTC: [FATAL ERROR]
 [1] java.lang.NullPointerException: null at edu.isi.pegasus.planner.common.PegasusConfiguration.updateSiteStoreAndOptions(PegasusConfiguration.java:211)
ERROR while logging metrics The metrics file location is not yet initialized

[tuto