Added PrivetHTTPResolution::Start for service name only

Added PrivetHTTPResolution::Start for service name only

Host:port can be resolved from service name.
Still old method is useful when client already know them.

BUG=461504
Committed: https://crrev.com/47f1b8cd0c50323b2577c44e7286a3eb26e22cbb
Cr-Commit-Position: refs/heads/master@{#318157}

[Vitaly Buka (NO REVIEWS), 2015-02-25 02:36:57]

vitalybuka@chromium.org changed reviewers:
+ alekseys@chromium.org

[Aleksey Shlyapnikov, 2015-02-25 02:41:00]

The CQ bit was checked by alekseys@chromium.org

[Aleksey Shlyapnikov, 2015-02-25 02:41:00]

lgtm

[commit-bot: I haz the power, 2015-02-25 02:41:43]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/948283005/20001

[commit-bot: I haz the power, 2015-02-25 02:47:19]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-02-25 02:47:20]

Try jobs failed on following builders:
  android_aosp on tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/android_aosp/bu...)

[Vitaly Buka (NO REVIEWS), 2015-02-25 23:44:13]

The CQ bit was checked by vitalybuka@chromium.org

[Vitaly Buka (NO REVIEWS), 2015-02-25 23:44:14]

The patchset sent to the CQ was uploaded after l-g-t-m from
alekseys@chromium.org
Link to the patchset: https://codereview.chromium.org/948283005/#ps40001 (title:
"Wed Feb 25 15:43:16 PST 2015")

[commit-bot: I haz the power, 2015-02-25 23:45:42]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/948283005/40001

[commit-bot: I haz the power, 2015-02-26 00:35:35]

Committed patchset #3 (id:40001)

[commit-bot: I haz the power, 2015-02-26 00:36:48]

Patchset 3 (id:??) landed as
https://crrev.com/47f1b8cd0c50323b2577c44e7286a3eb26e22cbb
Cr-Commit-Position: refs/heads/master@{#318157}