catkin_make doesn't handle colorizing of unicode text properly

We're building a couple third party packages using catkin, and wrapping their build systems. Some of them output non-ascii characters, which breaks the colorizing in catkin:

```
UnicodeEncodeError: 'ascii' codec can't encode character u'\u2018' in position 38: ordinal not in range(128)
<caktin_make> color formatting problem: 'ascii' codec can't encode character u'\u2018' in position 38: ordinal not in range(128)
Traceback (most recent call last):
  File "/opt/ros/groovy/lib/python2.7/dist-packages/catkin/builder.py", line 132, in run_command_colorized
    out.write(unicode(colorize_line(line)))
  File "/opt/ros/groovy/lib/python2.7/dist-packages/catkin/builder.py", line 58, in colorize_line
    cline = str(sanitize(line))
```