Incorrect module load causes missing module user warning with 7.50

I forgot to add the locale module as a dependency for this patch. It's included here. We're only using it for the country list, so I'm not sure if we want to include the whole module in order to pull in that function via the module_load_include or if want to go another route. I'll post a patch below that doesn't require a new dependency.

This patch also resolves the issue, but does not introduce a new module dependency like patch #5.

@markdorison: I did a check for the approach in #6 and I see that the system module does use a similar pattern to call the country_get_list() function from locale, pathauto and webform are other contrib modules that uses the include_once pattern instead of adding a dependency.

I have tried applying #5 on an installation that doesn't have locale enabled, and it maintains the same error message until I either:
1) Disable recurly and re-enable the module.
2) Enable the locale module manually.