Large refactoring

Related to: https://github.com/rahmatawaludin/laravel-notes/issues/3

I changed most of the code, I tried to keep commits clean but here are my notes:

[x] PSR4
[x] Separate Grep and PHP lookup providers. Choose according to the plataform.
[x] Travis setup (still need to add badges for Travis, Coveralls, Packagist, etc.)
[x] Updated README doc
[x] Both Lookup providers can filter for X type and add types to the default ones
[x] Code styling, parallel lint, mess detector
[x] Code coverage almost at 100%.
[x] NotesCommand now just set options, calls the provider and display results, no logic there

**Note**: to ease the pain on parsing lines, I made a change where only notes prepended with **@** will get noticed.

If you want we can discuss more changes on IRC. Thanks!