Allow setting textAllCaps to change capitalization for month name

[jarettmillard]

This will allow you to set android:textAllCaps="false" on the month name style to remove the capitalization. If the device's Android version is too old to support textAllCaps, the capitalization is still done in code for backwards compatibility.

[cvarier]

This change is absolutely necessary as we need a convenient way to modify the textAllCaps property, and currently the only way to do that is to override this method.