Bump to 3.15 alpha

Signed-off-by: Andy Scherzinger <info@andy-scherzinger.de>

build.gradle

@@ -85,7 +85,7 @@ repositories {
 
 // semantic versioning for version code
 def versionMajor = 3
-def versionMinor = 14
+def versionMinor = 15
 def versionPatch = 0
 def versionBuild = 0 // 0-50=Alpha / 51-98=RC / 90-99=stable