Add 'context' parameter to get_console_output()

The get_console_output() that is called from 'nova'
have two parameters 'context' and 'instance'.

Change-Id: I56c8a01ad00f62e6be5fa525c8971c5e29fc5098
Closes-Bug: #1310132
Merge "Add 'context' parameter to get_console_output()"