Remove UserSync url from config.go (prebid#1049)

* Gamma SSP Adapter

* Add Gamma SSP server adapter

* increase coverage

* Fix conflict with base master

* Add check MediaType for Imp

* Implement  Multi Imps request

* Changes requested

* remove bad-request

* increase coverage

* Remove duplicate test file

* Update gamma.go

* Update gamma.go

* Update gamma.go

* Update config.go

Remove Gamma User Sync Url from config

config/config.go

@@ -467,7 +467,7 @@ func (cfg *Configuration) setDerivedDefaults() {
 	setDefaultUsersync(cfg.Adapters, openrtb_ext.BidderEmxDigital, "https://cs.emxdgt.com/um?ssp=pbs&gdpr={{.GDPR}}&gdpr_consent={{.GDPRConsent}}&redirect="+url.QueryEscape(externalURL)+"%2Fsetuid%3Fbidder%3Demx_digital%26uid%3D%24UID")
 	setDefaultUsersync(cfg.Adapters, openrtb_ext.BidderEPlanning, "https://ads.us.e-planning.net/uspd/1/?du=https%3A%2F%2Fads.us.e-planning.net%2Fgetuid%2F1%2F5a1ad71d2d53a0f5%3F"+url.QueryEscape(externalURL)+"%2Fsetuid%3Fbidder%3Deplanning%26gdpr%3D{{.GDPR}}%26gdpr_consent%3D{{.GDPRConsent}}%26uid%3D%24UID")
 	// openrtb_ext.BidderFacebook doesn't have a good default.
-	setDefaultUsersync(cfg.Adapters, openrtb_ext.BidderGamma, "https://hb.gammaplatform.com/adx/sync/?gdpr={{.GDPR}}&consent={{.GDPRConsent}}&rurl="+url.QueryEscape(externalURL)+"%2Fsetuid%3Fbidder%3Dgamma%26gdpr%3D{{.GDPR}}%26gdpr_consent%3D{{.GDPRConsent}}%26uid%3D%24UID")
+	// openrtb_ext.BidderGamma doesn't have a good default.
 	setDefaultUsersync(cfg.Adapters, openrtb_ext.BidderGrid, "https://grid.bidswitch.net/sp_sync?sp_id=prebid&redir="+url.QueryEscape(externalURL)+"%2Fsetuid%3Fbidder%3Dgrid%26gdpr%3D{{.GDPR}}%26gdpr_consent%3D{{.GDPRConsent}}%26uid%3D%24UID")
 	setDefaultUsersync(cfg.Adapters, openrtb_ext.BidderGumGum, "https://rtb.gumgum.com/usync/prbds2s?gdpr={{.GDPR}}&gdpr_consent={{.GDPRConsent}}&r="+url.QueryEscape(externalURL)+"%2Fsetuid%3Fbidder%3Dgumgum%26gdpr%3D{{.GDPR}}%26gdpr_consent%3D{{.GDPRConsent}}%26uid%3D")
 	setDefaultUsersync(cfg.Adapters, openrtb_ext.BidderImprovedigital, "https://ad.360yield.com/server_match?gdpr={{.GDPR}}&gdpr_consent={{.GDPRConsent}}&r="+url.QueryEscape(externalURL)+"%2Fsetuid%3Fbidder%3Dimprovedigital%26gdpr%3D{{.GDPR}}%26gdpr_consent%3D{{.GDPRConsent}}%26uid%3D%7BPUB_USER_ID%7D")