Sequence bugfixes and AJAX pacer.
All ZMenus pointed to same variant in flanking seq.

Explicitly remove v parameter.
Changed text to be consistent with menus and buttons
Changed instances of 'datahub' in user interface to 'trackhub'
Added new fieldset so we can show a different label on the trackhub URL input
Merging commit from pull request (from master)
Text sequence legend fixes.
Fix broken BLAST sequence views.
Sequence key bugfixes.
Emty key removal. Again!
Add more info to the deprecated warning
Changed button text to 'Download alignment'
Disable download when no alignment chosen
Change the title of the hover menu too
hover_label's className just needs to be unique
Remove species name from track caption

...  to allow more room for region name
Display gene name in Phenotype Location page table
Wrong file extension for PSI format
Use the HTML tags in the HTML render
Do not link out if we're missing the extra data

If we haven't included the statistics, parameters, etc, data for a pairwise
alignment, we shouldn't provide a link to that page