Checking for filters with nil values.

Hard to see where/when this started happening to have just put in a check so that it doesn't try to iterate over nil.
Merge pull request #1131 from opf/bug-6361-timelines-initial-display

Checking for filters with nil values.
Gave the column header links the apparently standard empty javascript call.
Merge pull request #1135 from opf/bug-6472-tab-through-column-headers

Can now tab through column headers
Stopping the NaN/undefined crap from showing on pagination during load.
Flesh out test for tablePagination directive

Signed-off-by: Alex Coles <alex@alexbcoles.com>
Merge pull request #1136 from opf/bug-6469-hide-pagination-during-load

Stopping the NaN/undefined crap from showing on pagination during load.
Did a bit of hacking to get grouping by custom values working again.
Fixed group totals for non custom number values
Made a work packages helper test class and added tests for getRowObjectContent.