Make file-related log messages more informative

Let's make file-related log messages more informative, as follows:
* include the file location when referring to a file
* use a more informative term: prefs -> preferences

src/main/java/seedu/address/MainApp.java

@@ -79,14 +79,17 @@ private Model initModelManager(Storage storage, ReadOnlyUserPrefs userPrefs) {
         try {
             addressBookOptional = storage.readAddressBook();
             if (!addressBookOptional.isPresent()) {
-                logger.info("Creating a new data file populated with a sample AddressBook");
+                logger.info("Creating a new data file " + storage.getAddressBookFilePath()
+                        + " populated with a sample AddressBook.");
             }
             initialData = addressBookOptional.orElseGet(SampleDataUtil::getSampleAddressBook);
         } catch (DataConversionException e) {
-            logger.warning("Data file not in the correct format. Will be starting with an empty AddressBook");
+            logger.warning("Data file at " + storage.getAddressBookFilePath() + " is not in the correct format."
+                    + " Will be starting with an empty AddressBook.");
             initialData = new AddressBook();
         } catch (IOException e) {
-            logger.warning("Problem while reading from the file. Will be starting with an empty AddressBook");
+            logger.warning("Problem while reading from the file " + storage.getAddressBookFilePath()
+                    + ". Will be starting with an empty AddressBook.");
             initialData = new AddressBook();
         }
 
@@ -118,12 +121,12 @@ protected Config initConfig(Path configFilePath) {
         try {
             Optional<Config> configOptional = ConfigUtil.readConfig(configFilePathUsed);
             if (!configOptional.isPresent()) {
-                logger.info("Creating new config file.");
+                logger.info("Creating new config file " + configFilePathUsed);
             }
             initializedConfig = configOptional.orElse(new Config());
         } catch (DataConversionException e) {
-            logger.warning("Config file at " + configFilePathUsed + " is not in the correct format. "
-                    + "Using default config properties");
+            logger.warning("Config file at " + configFilePathUsed + " is not in the correct format."
+                    + " Using default config properties.");
             initializedConfig = new Config();
         }
 
@@ -143,21 +146,22 @@ protected Config initConfig(Path configFilePath) {
      */
     protected UserPrefs initPrefs(UserPrefsStorage storage) {
         Path prefsFilePath = storage.getUserPrefsFilePath();
-        logger.info("Using prefs file : " + prefsFilePath);
+        logger.info("Using preference file : " + prefsFilePath);
 
         UserPrefs initializedPrefs;
         try {
             Optional<UserPrefs> prefsOptional = storage.readUserPrefs();
             if (!prefsOptional.isPresent()) {
-                logger.info("Creating new prefs file.");
+                logger.info("Creating new preference file " + prefsFilePath);
             }
             initializedPrefs = prefsOptional.orElse(new UserPrefs());
         } catch (DataConversionException e) {
-            logger.warning("UserPrefs file at " + prefsFilePath + " is not in the correct format. "
-                    + "Using default user prefs");
+            logger.warning("Preference file at " + prefsFilePath + " is not in the correct format."
+                    + " Using default preferences.");
             initializedPrefs = new UserPrefs();
         } catch (IOException e) {
-            logger.warning("Problem while reading from the file. Will be starting with an empty AddressBook");
+            logger.warning("Problem while reading from preference file " + prefsFilePath
+                    + ". Will be starting with an empty AddressBook.");
             initializedPrefs = new UserPrefs();
         }