Adding check on stanford license for information in __init__ and to stop processing

in insarApp.py and isceApp.py because of their dependencies on licensed code files.

__init__.py

@@ -47,3 +47,14 @@ try:
 except KeyError:
     print('Using default ISCE Path: %s'%(isce_path))
     os.environ['ISCE_HOME'] = isce_path
+
+try:
+    from . license import stanford_license
+except:
+    print("This is the Open Source version of ISCE.")
+    print("Some of the workflows depend on a separate licensed package.")
+    print("To obtain the licensed package, please make a request for ISCE")
+    print("through the website: https://download.jpl.nasa.gov/ops/request/index.cfm.")
+    print("Alternatively, if you are a member, or can become a member of WinSAR")
+    print("you may be able to obtain access to a version of the licensed sofware at")
+    print("https://winsar.unavco.org/software/isce")

applications/insarApp.py

@@ -1197,6 +1197,13 @@ class Insar(_InsarBase):
 
 
 if __name__ == "__main__":
+    if not isce.stanford_license:
+        print("This workflow requires the Stanford licensed code elemnts.")
+        print("Unable to find the license information in the isce.stanford_license file.")
+        print("Please either obtain a stanford license and follow the instructions to")
+        print("install the stanford code elements or else choose a different workflow.")
+        raise SystemExit(0)
+    else:
         #make an instance of Insar class named 'insarApp'
         insar = Insar(name="insarApp")
         #configure the insar application

applications/isceApp.py

@@ -1786,6 +1786,13 @@ class IsceApp(Application, FrameMixin):
 
 
 if __name__ == "__main__":
+    if not isce.stanford_license:
+        print("This workflow requires the Stanford licensed code elemnts.")
+        print("Unable to find the license information in the isce.stanford_license file.")
+        print("Please either obtain a stanford license and follow the instructions to")
+        print("install the stanford code elements or else choose a different workflow.")
+        raise SystemExit(0)
+    else:
         #create the isce object
         isceapp = IsceApp(name='isceApp')
         #configure the isceapp object