Show annotations when listing tags

[robmoss]

@nefeltellioglu suggested using git tag -n when listing tags (§2.11 How to create and use tags), so that the first line of each tag annotation is included in the output.

For example, in my pypfilt repository running git tag produces:

0.1.0
0.1.1
0.1.2
0.2.0
...

and running git tag -n produces:

0.1.0           pypfilt 0.1.0
0.1.1           pypfilt 0.1.1
0.1.2           pypfilt 0.1.2
0.2.0           pypfilt 0.2.0
...

Admittedly, my annotations don't provide any extra information, but this is definitely a good idea.