ringtones: use qt API to get ringtones path and remove redundant folder

Use qt applicationDirPath to get ringtones path to avoid the complexity
of using windows API, and remove redundant ringtones folder.

Gitlab: #41
Change-Id: I5ae95531fb0e7627cdddb61334420bae3f37848b

ringtones/Makefile.am

-ringringtonesdir = $(datadir)/ring/ringtones
-dist_ringringtones_DATA = \
-	konga.ul\
-	default.wav \
-	default.opus

ringtones/default.opus.LICENSE

-Original file name: 171324__swidmark__ringtone.wav
-Download location: https://freesound.org/people/swidmark/sounds/171324
-Uploader: https://freesound.org/people/swidmark
-License: CC0 1.0 Universal (CC0 1.0) (https://creativecommons.org/publicdomain/zero/1.0/)

ringtones/default.wav.LICENSE

-Original file name: 171324__swidmark__ringtone.wav
-Download location: https://freesound.org/people/swidmark/sounds/171324
-Uploader: https://freesound.org/people/swidmark
-License: CC0 1.0 Universal (CC0 1.0) (https://creativecommons.org/publicdomain/zero/1.0/)

src/utils.cpp

@@ -197,12 +197,7 @@ QString
 Utils::GetRingtonePath()
 {
 #ifdef Q_OS_WIN
-    TCHAR workingDirectory[MAX_PATH];
-    GetCurrentDirectory(MAX_PATH, workingDirectory);
-
-    QString ringtonePath = QString::fromWCharArray(workingDirectory);
-    ringtonePath += QStringLiteral("\\ringtones\\default.opus");
-    return ringtonePath;
+    return QCoreApplication::applicationDirPath() + "\\ringtones\\default.opus";
 #else
     return QString("/usr/local");
 #endif