Capitalized iso suffixs not seen by cdrom. Make them case insensitive.

vrtManager/create.py

@@ -38,7 +38,7 @@ class wvmCreate(wvmConnect):
             except:
                 pass
             for img in stg.listVolumes():
-                if img.endswith('.iso'):
+                if img.lower().endswith('.iso'):
                     pass
                 else:
                     images.append(img)

vrtManager/instance.py

@@ -830,7 +830,7 @@ class wvmInstance(wvmConnect):
                 except:
                     pass
                 for img in stg.listVolumes():
-                    if img.endswith('.iso'):
+                    if img.lower().endswith('.iso'):
                         iso.append(img)
         return iso