Freeze the rally version
Freeze the rally version

1. Installed latest released version of rally as 0.8.1
2. Removed outdated description

Change-Id: Iebc8c65809dc814fe51aab27f0721b01fd6feb4b
Signed-off-by: helenyao <3eb787ab97713f28a85d5a5517e91512dad61756@huawei.com>

opnfv/functest,mywulin/functest,mywulin/functest,opnfv/functest