CLOUDSTACK-5428: support NetScaler to be configured exclusively for GSLB
service and not used for LB

Fix adds a boolean flag to addNetscalerLoadBalancer api, which
will mark added NetScaler for exclusive GSLB service. A netscaler marked
as exclusive gslb service provider is not picked for any guest network's
lb provider.

Conflicts:
	engine/schema/src/com/cloud/network/dao/ExternalLoadBalancerDeviceVO.java
	plugins/network-elements/f5/src/com/cloud/network/element/F5ExternalLoadBalancerElement.java
	plugins/network-elements/netscaler/src/com/cloud/api/commands/AddNetscalerLoadBalancerCmd.java
	plugins/network-elements/netscaler/src/com/cloud/api/response/NetscalerLoadBalancerResponse.java
	plugins/network-elements/netscaler/src/com/cloud/network/element/NetscalerElement.java
	server/src/com/cloud/network/ExternalLoadBalancerDeviceManager.java
	server/src/com/cloud/network/ExternalLoadBalancerDeviceManagerImpl.java
	setup/db/db/schema-421to430.sql
CLOUDSTACK-5431: permit 'http' as service type for GSLB rule

Conflicts:
	api/src/com/cloud/region/ha/GlobalLoadBalancerRule.java
	api/src/org/apache/cloudstack/api/command/user/region/ha/gslb/CreateGlobalLoadBalancerRuleCmd.java
Fixed CLOUDSTACK-5436

Fixed few RAT issues reported for new additions of files to repo.
Signed-off-by: Santhosh Edukulla <Santhosh.Edukulla@citrix.com>
Signed-off-by: Abhinandan Prateek <aprateek@apache.org>