Update xpath to only find the next table
Update xpath to only find the next table

result_table_location = "//*[@class='summary-item-heading'][normalize-space(text())=\"#{table_heading}\"]/following-sibling::table[1]

will find the next sibling table on the page. Because we don't render a table element for empty tables this means that it will find the next 'non-empty table'

For example if out buyers homepage looks like this:

```
Unpublished requirements
You don’t have any unpublished requirements

Published requirements
You don’t have any published requirements

Closed requirements
Name	Closed	Responses
Some requirement	Wednesday 15 March 2017	View responses
```

And we look for the 'Published requirements' table we will find the next sibling table of the Published requirements header.
The next sibling _table_ is actually the closed requirements table.

The new xpath finds the next sibling _anything_

alphagov/digitalmarketplace-functional-tests,alphagov/digitalmarketplace-functional-tests,alphagov/digitalmarketplace-functional-tests