Adding pluralization

[mochetts]

This adds the pluralization enhancement asked in issue #33.

The idea is the same as Laravel follows. Have a pipe "|" separator to define plurals in each locale.

It should support what was supported so far (as it re-uses the translation functionality from before) plus adding a transformation when pipes are present in the locale and the user calls function $tc or Vue.tc.

So if the locale is
{some_placeholder: 'singular | plural'}

The result of
$tc('some_placeholder, 2)

Would be string 'plural'

[coveralls]

Coverage increased (+0.4%) to 91.388% when pulling 6a431ec on mmochetti:pluralization into 3e1bf8d on kazupon:dev.

[kazupon]

Awesome !! 💯
Thanks!!