Implement Ordinal Pipe

[tanayv]

This pipe will add an ordinal suffix (eg. st, nd, rd) to a number, which is useful for displaying ranks in leaderboards and so on.

Examples:

{{ 1 | ordinal }} <!-- 1st -->
{{ 22 | ordinal }} <!-- 22nd -->
{{ 523 | ordinal }} <!-- 523rd -->
{{ 15 | ordinal }} <!-- 15th -->

[coveralls]

Coverage remained the same at 100.0% when pulling e852b04fd1e6263ea86d03e444c59cdf36d289f5 on tanayv:ordinal-pipe into 06df035b292254bd2486f779fbfe40c1076f8346 on fknop:master.

[tanayv]

Made the changes! Thanks.