passage-ref: i9nalize the "lines 3-4" message

Summary:
This internationalizes the "line 3" or "lines 3-4" or "lines ?-?"
output of a passage ref widget.

The lineRange/lineNumber variable is to allow translators to reposition
the "3-4" relative to the "lines". I'm not sure if this is the perfect
way to do this, since one could desire to change the representation of
"3-4" itself, but that gets awkward with the EN_DASH not being a raw
string literal (we could make it one if this becomes significant, but
until then I prefer ascii source code when possible).

(Note: this is all currently a bit moot since we don't intend to
translate SAT content, but is worthwhile for completeness.)

Test Plan:
make a passage widget with one line, multi-line, and missing
passage-refs:
[sample item](http://localhost:9000/test.html#content=%7B%22question%22%3A%7B%22content%22%3A%22%5B%5B%E2%98%83%20passage%202%5D%5D%5Cn%5Cn%5B%5B%E2%98%83%20passage-ref%201%5D%5D%5Cn%5Cn%5B%5B%E2%98%83%20passage-ref%202%5D%5D%5Cn%5Cn%5B%5B%E2%98%83%20passage-ref%203%5D%5D%22%2C%22images%22%3A%7B%22https%3A%2F%2Fka-perseus-graphie.s3.amazonaws.com%2Fda8df81c78b22f5c69d477d8eabfb583968eaf84.png%22%3A%7B%22width%22%3A400%2C%22height%22%3A70%7D%2C%22https%3A%2F%2Fka-perseus-graphie.s3.amazonaws.com%2Fb59fc02ca1aae800977b8793ed22f647a1aa75ee.png%22%3A%7B%22width%22%3A425%2C%22height%22%3A150%7D%7D%2C%22widgets%22%3A%7B%22passage%202%22%3A%7B%22type%22%3A%22passage%22%2C%22graded%22%3Atrue%2C%22options%22%3A%7B%22passageText%22%3A%22this%20is%20a%20aklsdj%20fkldjafs%20lkdfja%20kldfjflda%20l%3Bdjsfkldfsajdsfkl%3Bdsf%20jalkdfsj%20dsflkfjdsa%20l%3Bkdfajdfl%20%3Bdfsajdlfks%3Bj%20dflkdsfj%20dslfkj%20dsflkdsfj%20%7B%7Bklsdfjsdflk%20fdsjlksdf%20jfsdlklj%20fdslkfdsj%20lkfsdjsdflkjdsfkl%20dsfj%20lkdfsjdsfl%7D%7D%5Cn%5Cndfskjladfafjklfdjfdsklsd%20fjl%20d%20sfkj%20ds%20f%20lkdfsj%20l%20k%20fd%20s%20jdfskl%20sfdjkl%20dsfjf%20d%20lk%20d%20fs%20j%20dl%20k%20s%20j%20s%20dfkldsfjdsklf%5Cn%5Cndkl%20jkfdsah%20fjkfjd%20a%20djjfdaldfajs%20kdfsajal%3Bkdfasjkdfsakj%20dfskfd%20djfkdf%20dkajdk%20jadfkjadf%20__%7B%7Bdafksjkdfkjfdk%7D%7D__%20oiwjhqwe%20oew%20ewj%20weroijkojdsx%2Cmnacx%20lkhdskldsfz%20dskl%20k%22%2C%22showLineNumbers%22%3Atrue%7D%2C%22version%22%3A%7B%22major%22%3A0%2C%22minor%22%3A0%7D%7D%2C%22passage-ref%201%22%3A%7B%22type%22%3A%22passage-ref%22%2C%22graded%22%3Atrue%2C%22options%22%3A%7B%22passageNumber%22%3A2%2C%22referenceNumber%22%3A1%7D%2C%22version%22%3A%7B%22major%22%3A0%2C%22minor%22%3A0%7D%7D%2C%22passage-ref%202%22%3A%7B%22type%22%3A%22passage-ref%22%2C%22graded%22%3Atrue%2C%22options%22%3A%7B%22passageNumber%22%3A2%2C%22referenceNumber%22%3A2%7D%2C%22version%22%3A%7B%22major%22%3A0%2C%22minor%22%3A0%7D%7D%2C%22passage-ref%203%22%3A%7B%22type%22%3A%22passage-ref%22%2C%22graded%22%3Atrue%2C%22options%22%3A%7B%22passageNumber%22%3A1%2C%22referenceNumber%22%3A1%7D%2C%22version%22%3A%7B%22major%22%3A0%2C%22minor%22%3A0%7D%7D%7D%7D%2C%22answerArea%22%3A%7B%22type%22%3A%22multiple%22%2C%22options%22%3A%7B%22content%22%3A%22%22%2C%22images%22%3A%7B%7D%2C%22widgets%22%3A%7B%7D%7D%2C%22calculator%22%3Afalse%7D%2C%22itemDataVersion%22%3A%7B%22major%22%3A0%2C%22minor%22%3A1%7D%2C%22hints%22%3A%5B%5D%7D)

Then changed $_ to capitalize all non-variables in interpolated strings,
and saw that "line"/"lines" were in all-caps in the above item.

For reference the khan-exercises diff to produce this is:

    diff --git i/local-only/i18n.js w/local-only/i18n.js
    index 961125e..c54a438 100644
    --- i/local-only/i18n.js
    +++ w/local-only/i18n.js
    @@ -84,6 +84,9 @@
                     "%(" + split[i] + ")s" :
                     replaceWith;
             }
    +        for (var i = 0; i < split.length; i += 2) {
    +            split[i] = split[i].toUpperCase();
    +        }
             return split;
         };

Reviewers: michelle, alpert

Reviewed By: alpert

Differential Revision: http://phabricator.khanacademy.org/D12161