line-up: add test cases for ordinal numbers that are multiples of 11/12/13 and update the descriptions

[QuentinNev]

See discussion: http://forum.exercism.org/t/line-up-exercise-missing-test-case-for-ordinal-suffix-multiples-of-11-12-13-outside-the-teens-range-are-not-covered/67586

Summary

Adds test cases for line-up covering ordinal numbers that are multiples of 11, 12, or 13 outside the 11–13 range itself.
It also reformulate the descriptions to be more explicit about what it's testing.

Problem

Uncovered multiples of 11, 12 and 13

The test suite for line-up does not include any numbers whose last two digits are a multiple of 11, 12, or 13 outside the 11–13 range itself (e.g. 22, 24, 33, 36, 44, 52, 60, 63, 65, 72, 78, 91, 96…).

This gap allows an incorrect implementation to pass. For example, a common bug is checking divisibility instead of range when handling the "teens" exception:

if (last2 % 11 === 0 || last2 % 12 === 0 || last2 % 13 === 0) return `${number}th`;

This looks like it's meant to handle the 11th/12th/13th exception (and does, since 11%11=0, 12%12=0, 13%13=0), but it also incorrectly catches any other multiple of 11, 12, or 13 (such as 22, 33, 44, 52, 91) and returns "th" for them instead of the correct "nd"/"rd"/"st".

Unclear descriptions

As proposed in the discussion, the descriptions weren't clear enough about what they're covering

Changes

• Added 5 new test cases: 22, 33, 44, 52, 91, covering both the exceptional (nd/rd/st) cases that expose the bug and one non-exceptional (th) case as a regression check.
• Updated descriptions to specify if it's a multiple of 11, 12 or 13 and the expected suffix

[keiravillekode]

As requested in the forum, one or more of the numbers should be greater than 255. For example, 891, 923 or 972

[IsaacG]

...and please make the descriptions more descriptive of the purpose of the tests (i.e. they should convey what the test adds/what gap they cover)

[IsaacG]

@QuentinNev Any updates here?