More robust error handling and logging

Catch and log InputError()
Catch and log ValueError() and report back to the API user

Change-Id: I1d7414baa4a84106439c37ad36be3578356a3371
diff --git a/util.py b/util.py
index e1de89d..e71e907 100644
--- a/util.py
+++ b/util.py
@@ -103,11 +103,12 @@
             else:
                 raise InputError("Unknown db_query command \"%s\"" % command)
 
-        except InputError:
+        except InputError as e:
+            logging.error('perform_db_query(%s) got error %s', command, e)
             raise
-
-#        except:
-#            raise InputError("Invalid input in query")
+        except ValueError as e:
+            logging.error('perform_db_query(%s) got error %s', command, e)
+            raise InputError("Invalid value in API call argument: %s" % e)
 
         return ret
 
@@ -135,11 +136,12 @@
             else:
                 raise InputError("Unknown daemon_query command \"%s\"" % command)
 
-        except InputError:
+        except InputError as e:
+            logging.error('perform_daemon_query(%s) got error %s', command, e)
             raise
-
-#        except:
-#            raise InputError("Invalid input in query")
+        except ValueError as e:
+            logging.error('perform_daemon_query(%s) got error %s', command, e)
+            raise InputError("Invalid value in API call: %s" % e)
 
         return ret
 
@@ -177,11 +179,12 @@
             else:
                 raise InputError("Unknown db_update command \"%s\"" % command)
 
-        except InputError:
+        except InputError as e:
+            logging.error('perform_db_update(%s) got error %s', command, e)
             raise
-
-#        except:
-#            raise InputError("Invalid input in query")
+        except ValueError as e:
+            logging.error('perform_db_update(%s) got error %s', command, e)
+            raise InputError("Invalid value in API call: %s" % e)
 
         return ret
 
@@ -212,11 +215,11 @@
                 raise InputError("Unknown query command \"%s\"" % command)
 
         except InputError as e:
-            logging.debug('got error %s', e)
+            logging.error('perform_vlan_update(%s) got error %s', command, e)
             raise
-
-#        except:
-#            raise InputError("Invalid input in query")
+        except ValueError as e:
+            logging.error('perform_vlan_update(%s) got error %s', command, e)
+            raise InputError("Invalid value in API call: %s" % e)
 
         return ret