rerender remove the datatable buttons after rerender twice.

[jmelosegui]

After calling rerender function two times the datatable buttons disappear.

I have created a plunker reproducing this issue.

Repo steps:

1. Navigate to the plunker.
2. Click the "Reload Data" button twice.
   3 The "Test Button" disappears

Notice that I have to use rerender instead of reload due to #549

Hope you can fix one of those, but in the meantime can you suggest a version where reload works correctly?. So, maybe I can downgrade until these are fixed.

Thanks in advance !!!

[jmelosegui]

CC @cbarest