Fixes an issue when status name contains spaces

I tried to find a status by name, but got an error when that contains a space.

```ruby
client.Status.find("In Progress")
JIRA::HTTPError: ...
```

So then, I tried to find a status again by url-encoded name. That was OK.

```ruby
client.Status.find("In%20Progress")
=> #<JIRA::Resource::Status:...
```

I think client should accept non-url-encoded key value parameter. This is a patch.
Thanks!