Add some colors to pkg deletion messages

[ghost]

The idea is to colorize some messages I find important in the initial poudriere output of bulk, like which pkgs are deleted and for what reason: new version, dependency changed, options changed, etc...

Running this set of patches in production for a number of bulk runs / days now. Haven't tested all possible situations. Example screenshot here:

[bdrewery]

I like this, but I think we should limit to 1 color here. It can be simpler if we move the msg into delete_pkg as well and pass the reason as an argument.