Description of problem:
The command in the setDefaultGatway function in waagent is incorrect.

Version-Release number of selected component (if applicable):
WALinuxAgent-2.0.16-1.el6

How reproducible:
Always

Steps to Reproduce:
1. Prepare a VM on Azure and login.
2. Enable the verbose log. Enable the error log of the "setDefaultGateway" function in class AbstractDistro
# vi /etc/waagent.conf, set Logs.Verbose=y
# vi /usr/sbin/waagent, find the "setDefaultGatway" function in class AbstractDistro, set "chk_err=True"
3. service waagent restart
4. Check the /var/log/waagent.log

Actual results:
The set default gateway command is "/sbin/route add default gw172.19.0.1" which is incorrect, so that it cannot be executed successfully.

Messages in /var/log/waagent.log:
2016/04/08 02:52:39 Set default gateway: 172.19.0.1
2016/04/08 02:52:39 /sbin/route add default gw172.19.0.1
2016/04/08 02:52:39 ERROR:CalledProcessError.  Error Code is 7
2016/04/08 02:52:39 ERROR:CalledProcessError.  Command string was /sbin/route add default gw172.19.0.1
2016/04/08 02:52:39 ERROR:CalledProcessError.  Command result was SIOCADDRT: No such device

Expected results:
The set default gateway command is correct.

Additional info:
The root cause is there's no space between "gw" and gateway address in the setDefaultGateway function in class AbstractDistro.