[Accessibility] Tab focus order and screen reader text for column headers

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• This is a bug report, not a question on how to use the grid.
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• You have searched the open issues to see if this bug has been filed before. We don't want duplicate issues.
• You have reviewed the tutorials and documentation to ensure you are using the grid correctly. ui-grid.info
• You are using the latest version of the grid. Older versions are not patched or supported.
• You have provided steps to recreate your bug. A plunkr is even better.

http://ui-grid.info/docs/#!/tutorial/Tutorial:%20121%20Grid%20Menu

Here's a gif from the tutorials site. As it can be seen, there are two issues:

• When the keyboard focus is on the checkbox in the header row, on pressing the tab key, focus goes to the checkbox in the next row instead of moving to the next column header.
• When the keyboard focus reaches the column headers, the screen reader announces the row and the column numbers incorrectly: In case of the 'Gender' header (3rd column header including the checkboxes), 'Column 2' is announced and for the complete header row, excluding the checkboxes is read as 'Row 19', counting 18 rows for the check boxes.