rif/cache2go — pull request #7 by ZeissS (2014-11-18 17:06:23+00:00)
Title: Make errors accessable

This PR moves all calls to `errors.New()` into variables so a user of this library can more easily compare them, e.g. to avoid to call `Exists()` first.

```
item, err := cache.Value("somekey")
if err != nil {
if err == cache2go.ErrKeyNotFound {
// do something
}
// Abort horrible
}
```