nice-sbt-settings v0.5.0 release

- [x] address #23
- [x] update literator and taglist plugins (easy)
- [x] fix: error messages instead of exceptions  
   this likely was my local problem; solved with `set every traceLevel := -1` (suppress stacktraces)
- [ ] fix: `pushApiDocsToGHPagesAction` check vcs operations like remote fetching
- [x] change log-level for `FIXME` tags to error and ask to continue if there are some