Fix href’s in project and language tabs

The URLs were relative to the current tab, so in Translate tab, for
example, you end with wrong URLs like:

  projects/terminology/translate/notices
  projects/terminology/translate/admin.html
Fix translate-table margins in Chrome

-1.5em is way too much, apparently Firefox contains the table to its
parent element(s) so only a -0.4em was effective, but not in Chrome
resulting in the boy encroaching upon the tabs.

Why this wasn’t happening before, I don’t know.
Don’t filter units based on permissions here

I don’t see what is the point for that, the editor already checks for
permissions, and the filtering here was broken anyway (one needs either
explicit permission or super user, which is not how permission checks
usually work).
Don't fail if garbage has been passed
Re-enable indexing support

This fixes bug 3028 by iterating over all translation projects of the
given Pootle path.