Changed the label from Edit Rules to Manage Rules

In the Access & Security' category under Project tab,
for each security group, there is an option to edit
the rules. Clicking this button, lists all the rules
for a given security group and from there we can
add/delete rules. Since there is no support for security
group rule editing provided by Nova/Neutron, in this fix
the label of the 'Edit Rules' button was changed to
'Manage Rules' instead.

Closes-Bug: 1210513

Change-Id: I644c95b2f0147f5f59b543fd1eb9748ee4eb7e19
Merge "Changed the label from Edit Rules to Manage Rules"