add support for LWP user agents

[mtmail]

Geo::Coder::OpenCage allows to set a user agent (ua parameter) which defaults to HTTP::Tiny. Documentation says "Useful if for example you want to specify that something like LWP::UserAgent::Throttled for rate limiting."

Later in code logic

my $response = $self->{ua}->get($URL);`
...
$response->{reason}
...
$response->{content}

That fits the HTTP::Tiny interface.

But the more common LWP user agents as well, e.g. LWP::Simple or LWP::UserAgent::Throttled return a HTTP::Response instance with status_line and decoded_content data accessors.

[freyfogle]

probably the easiest thing here is just to change the documentation ;-)