Default to en_US

This fixes a few tests that were failing as my default locale is not
en_US.
Fix corrupted global state.

On my non en_US machine tests following this would fail as my default
locale of en_CA was picked up.
Add templates option to numbers()

Much like the templates options in FormHelper, this option lets you set
the templates for one numbers() call. Or have numbers() use different
templates than the rest of your pagination buttons.

Refs #4171
Fix undefined variable error.
Merge pull request #4209 from markstory/issue-4171

Add templates option to PaginatorHelper::numbers() and fix failing tests