Prepare for release 0.5.4

Author: Rafael Baboni Dominiquini

build.gradle

@@ -23,6 +23,6 @@ ext {
     buildToolsVersion = '23.0.1'
     targetSdkVersion = 22
     minSdkVersion = 14
-    versionCode = 15
-    versionName = "0.5.3"
+    versionCode = 16
+    versionName = "0.5.4"
 }