Update WellBehavedFX to 0.2.1-SNAPSHOT version

This is in preparation to moving from the current approach to handling user input to the new approach via the experimental package in WellBehavedFX:

Author: JordanMartinez

richtextfx/build.gradle

@@ -11,7 +11,7 @@ dependencies {
     compile (group: 'org.fxmisc.flowless', name: 'flowless', version: '0.5-SNAPSHOT') {
         transitive = false
     }
-    compile group: 'org.fxmisc.wellbehaved', name: 'wellbehavedfx', version: '0.2'
+    compile group: 'org.fxmisc.wellbehaved', name: 'wellbehavedfx', version: '0.2.1-SNAPSHOT'
     testCompile group: 'junit', name: 'junit', version: '[4.0,5)'
 }