Added option to change ActionMode title

I have added a method to MultiChoiceAdapter interface that receive the count of selected items and returns the title for ActionMode. By default it returns Resources.getQuantityString(R.plurals.selected_items, count, count) but the user can extends this method in Adapter.

I have changed the plugin gradle version to compile successfully with Gradle 1.10

I changed the activity names in samples and I have fixed a bug in the class com.manuelpeinado.multichoiceadapter.extras.actionbarsherlock.MultiChoiceAdapterHelper

Hope this helps