Changed implementation of proxy setup

Changed the setup_http_proxy method to setup_proxy.
The same arguments are used as before. This change includes
workarounds for pulp proxy configuration. However, until BZ1114083
is fixed, easier proxy support will not be possible.
What are you trying to do here? Get an IP address?

```
[ichimonji10@beech:tmp]$ ping -c 1 google.com | grep 'icmp_seq'
64 bytes from iad23s07-in-f1.1e100.net (74.125.228.65): icmp_seq=1 ttl=54 time=53.2 ms
```

How about using `host`?

```
[ichimonji10@beech:tmp]$ host google.com
google.com has address 74.125.228.70
google.com has address 74.125.228.67
google.com has address 74.125.228.73
google.com has address 74.125.228.71
google.com has address 74.125.228.78
google.com has address 74.125.228.66
google.com has address 74.125.228.64
google.com has address 74.125.228.68
google.com has address 74.125.228.72
google.com has address 74.125.228.69
google.com has address 74.125.228.65
google.com has IPv6 address 2607:f8b0:4004:802::1002
google.com mail is handled by 20 alt1.aspmx.l.google.com.
google.com mail is handled by 50 alt4.aspmx.l.google.com.
google.com mail is handled by 40 alt3.aspmx.l.google.com.
google.com mail is handled by 30 alt2.aspmx.l.google.com.
google.com mail is handled by 10 aspmx.l.google.com.
```

Just grab the 1st address and split it.

    [ichimonji10@beech:tmp]$ host google.com | head -n 1 | awk '{print $4}'
    74.125.228.71