Fix an exception on setting locale to request header, as rubyst is common
to set locales with a symbol other than a string. When setting locale as
string `Conekta.locale = 'es'` everything works but when `Conekta.local = :es`
is set an exception happen at the point where locale is set on header,
exception is masked by the begin block when assigment happen an a misleading
error is shown:
Could not connect to https://api.conekta.io
Conekta::NoConnectionError
In the way that you are trapping errors the stack trace is lost and it is hard
to debug this kind of issues.
Merge pull request #10 from mariochavez/fix-exception-with-locales

Fix an exception on setting locale to request header