Fix parameter encoding issue

[jaronoff97]

The target allocator was only unencoding when a collector_id wasn't provided which made it so that the target for the collector was never returned. This also fixes the issue where the encoded URL wasn't provided correctly to the collectors

Closes #925

Evidence this works:

[ root@curl-jea:/ ]$ curl http://lightstep-collector-targetallocator:80/jobs/serviceMonitor%2Fcollector%2Fcoll
ector%2F0/targets
{"lightstep-collector-collector-2":{"_link":"/jobs/serviceMonitor%2Fcollector%2Fcollector%2F0/targets?collector_id=lightstep-collector-collector-2","targets":[{"targets":["0.0.0.0:8888"],"labels":null}]}}

          scrape_configs:
          - job_name: serviceMonitor/collector/collector/0
            honor_timestamps: true
            scrape_interval: 5s
            scrape_timeout: 5s
            metrics_path: /metrics
            scheme: http
            follow_redirects: true
            http_sd_configs:
            - follow_redirects: false
              url: http://lightstep-collector-targetallocator:80/jobs/serviceMonitor%2Fcollector%2Fcollector%2F0/targets?collector_id=$POD_NAME

[secustor]

A small nitpick, else lgtm.

[yuriolisa]

LGTM.

[yuriolisa]

@pavolloffay, could you please merge it?

[pavolloffay]

this should be moved to the second group