Description of problem:
in beta 3, after saving changes tohttp_proxy is is no longer possible to revert them

Version-Release number of selected component (if applicable):
5.7.0.13

How reproducible:
all the time

Steps to Reproduce:
1.under advanced configuration for the appliance set the http_proxy
2.save
3.log out
4. lkog in 
5. change http_proxy to be empty
6. save

Actual results:
the http_proxy continues to use the first value

Expected results:
http_proxy changes to using no proxy.

Additional info:
beta 3, trying to change http_proxy from squid.redhat.com to the default value did not work