Preserve interface param labels on release

[kassim]

    public interface OnMenuItemSelectionListener {
        void onMenuItemSelect(@IdRes int var1, int var2, boolean var3);

        void onMenuItemReselect(@IdRes int var1, int var2, boolean var3);
    }

is kinda hard to use without digging into the source, I'd advise configuring Proguard to ignore them

in fact, I'm not sure what Proguard would be needed on the library package at all considering it's open source

I'm using 'it.sephiroth.android.library.bottomnavigation:bottom-navigation:2.0.1-rc1'