Support rowspan in table for MIQ tag edit tables.

[mshriver]

The TODO has been recorded in SummaryTable in MIQ/Integration_tests/widgetastic_manageiq:

https://github.com/ManageIQ/integration_tests/blob/master/widgetastic_manageiq.py#L709

@mfalesni Suggested in PR review this should be implemented at the core and extended to widgetastic_manageiq.

Recording the TODO as an issue for visibility and tasking.

[mfalesni]

So, I think that if a field defines rowspan, the result should be a list of values, what do you think?

[mfalesni]

like column 1 defines rowspan, then the rows that happen to fall under the rowspan of column 1 shall be grouped in a list.