Move contest phase computation out of render_params
Add tests for phase computation and fix a few minor bugs

The bugs were:
- when in a post-contest phase, the start of that phase was computed
  without taking the extra_time into account;
- the starting_time was allowed to be before the start of the contest;
- when starting_time was not None we assumed it to be in the past, i.e.
  starting_time <= timestamp.
These were all conditions that didn't affect a "normal" contest.
Rewrite the phase computation function

Simplify it and support delay_time (reenabling its tests).
Add delay_time
Minor for pydoc types.
Update pot generation command.
Complete ja, it, fr, nl, ru translations and fix a string.

Thanks to all translators.

There was a typo "infinite an infinite number..." I just keeped the
translations as they are very likely to be correct.

I also removed the location info in all translations (as we started
doing a while ago) and old strings not useful anymore.
Completed lt translation.

Thanks to Vytis Banaitis.
Added competitions in README and missing bs translations.
Add CEOI 2014 to testimonals.

Also fix some punctuation.