Description of problem:
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Creating a router on CFME has an option to connect it to one network.
Assuming the router created successfully, there is no option to add additional network to the router.   


Version-Release number of selected component:
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5.7.0.12-rc2.20161123111642_a4a65ce

How reproducible:
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100%

Steps to Reproduce:
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1. Create a router 

Actual results:
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No option to and an interface (subnet) to the router

Expected result:
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Having an option under configuration to and an interface to selected router