Put Caliper annotations into a separate Maven module

```
Currently when I want to use the Caliper annotations to write a benchmark class
I need to add the dependency com.google.caliper:caliper to my project, which
brings a lot more transitive dependencies into my project, which makes life
hard.

If I understand Caliper correctly, all you need in order to write a benchmark
class are the Caliper annotations. Therefore I propose to provide a module with
just those annotations and without further dependencies which could be added to
almost every project without conflicts.

Of course this change would break the way, how Caliper is supposed to be
executed (according to the tutorial video), but I hope there is an easy
solution to this problem. Maybe a caliper-maven-plugin?
```

Original issue reported on code.google.com by `michael.tamm2` on 7 Aug 2013 at 3:32