[CRTP infra-vmware connector]Multiple vcenters connections support

[cgourdin]

Add to vmware connector the support of multiple vcenter connections.
The properties configuration (in /user/home/) file may be used with data like :
vcenter.login.1 = xxxxx
vcenter.password.1= xxxxx
vcenter.url.1=https://xxx.xxx.xxx.xxx/sdk
vcenter.login.2 = xxxxx
vcenter.password.2 = xxxx
vcenter.url.2=https://xxx.xxx.xxx.xxx/sdk
vcenter.login.n = xxxxx
vcenter.password.n = xxxx
vcenter.url.n=https://xxx.xxx.xxx.xxx/sdk
The connector may connect on all declared vcenters for all resources.
Add an attribute to vmfolders mixin "vcenter" with the url address to define on which vcenter is located the resource/link.
By default, the connector must use the first vcenter if the attribute is not set.

[cgourdin]

Check if Scalair need it for their use case. Will be reopened if needed.