Added Console Logging to HaaS

This patch adds console logging to HaaS by running ipmitool subprocesses that
log to files.  There is now an API call 'show_console' that displays the
contents of the console log to the user.  Log files are securely deleted when
nodes have a change in ownership.
Console Feature Cleanup

This patch cleans up some of the code added in this feature branch.
Additionally, this patch also makes it so the user is in charge of starting and
stopping console logging via the API, instead of logging always happening while
a node belongs to a project.  This ensures that a large number of unused
logging subprocesses are not running.
Removed unnecessary import in api.py

import os was not being used.
Fixed garbled stdout when logging console

HaaS serve would produce garbled output while logging from the console.  This
was fixed by redirecting stdin to a PIPE that is never read.  This happened
because ipmitool was casuing the shell to behave like a tty.
Fixed string alignment
Changed console_log_filename from db entry to function.

Instead of storing the console log filename in the database, it is now derived
using a helper function in the Node class.
Merge pull request #277 from ryabouza/console_feature

Added Console Logging to HaaS