CA-227062: update host/vm/sr selectors info-strings
CA-227062: update host/vm/sr selectors info-strings

The previous specification for vm, host and sr selectors was generically mentioning a lookup on name or uuid, where name was not a well specified parameter key.

Signed-off-by: Marcello Seri <34fd14c67154e888f6587d5c0e7eadd13aaf7ca7@citrix.com>

euanh/xen-api,thomassa/xen-api,thomassa/xen-api,srowe/xen-api,euanh/xen-api,srowe/xen-api,euanh/xen-api,euanh/xen-api,euanh/xen-api,Frezzle/xen-api,euanh/xen-api,thomassa/xen-api,Frezzle/xen-api,thomassa/xen-api,srowe/xen-api,thomassa/xen-api,Frezzle/xen-api,srowe/xen-api,thomassa/xen-api,srowe/xen-api,Frezzle/xen-api,Frezzle/xen-api