Added missing submission type attribute

Bulk actions performed offline were missing a value for this attribute.
We're adding it for consistency and completeness. Includes data migration
code.
Added ALLOWED_HOSTS to the template development settings
Make tipsy tooltips fully opaque
sorttable.js can perfectly deal with multiple thead rows

(assuming the first thead row contains the actual headers and the others contain non-sortable 'header' entries)
Use CSS selectors for even/odd row coloring in translation table

Conflicts:
	pootle/static/css/style.css
	pootle/static/js/editor.js
Under Windows, the "nl_langinfo" method is not available
Show spinner in the middle of edit row
Use try/except instead of checking the function existence