Implements a logger module following the PSR-3 specification

# PSR-3 Logger for lmvc-modules

This feature includes a logger following the [PSR-Standard](https://github.com/php-fig/fig-standards/blob/master/accepted/PSR-3-logger-interface.md). It follows interface, class and trait specifications given in the fig-standard.

## Checklist

- [x] Add and import interface specs
- [x] Add and import interface trait and abstract class specs
- [ ] Setup logger configuration in LVCConfig
- [ ] Decide upon directory structure for logs
- [ ] Implement storage engine for loggers' logs
- [ ] Add logs-directory to lmvc's `.gitignore`
- [ ] Decide upon integration with [ChomeLogger](http://craig.is/writing/chrome-logger)

## Questions

- Should storage always prepend (on top in editor) or append ('$ tail' works) to log-files
- Should the logger have a config value to automatically keep log files under a certain line limit
- Should the logger automatically split log files by day

Feel free to add comments, wishes or observations in other log libraries. It would be kinda good to get a decent set of the good parts in here and leave the complexity of bad parts out.