[TW-1689] confirmation prompt: Improve readability

_Daniel Shahaf on 2015-09-08T21:00:25Z says:_

```
% task 1,2,3 mod +foo
* Tags will be set to 'foo'.
Modify task 1 'one'? (yes/no/all/quit) y
Modifying task 1 'one'.
* Tags will be set to 'foo'.
Modify task 2 'two'? (yes/no/all/quit) y
Modifying task 2 'two'.
* Tags will be set to 'foo'.
Modify task 3 'three'? (yes/no/all/quit) y
Modifying task 3 'three'.
Modified 3 tasks.
```

The above output is not colorized.

The replaceable parts should be colorized so it is easy for the eye to identify them. At least the description (`three`) should be colorized; the other replaceables either are volatile (id's) or are user-specified argument to the modification operation (the tags being added).

Instead of coloring the text, it could be laid out differently, again in a manner that makes the interesting part — the description — is easy for the eye to catch. For example:

```
* Tags will be set to 'foo'.
Modify task:
[1] 'one'
(yes/no/all/quit) y
Modifying task 1 'one'.
```