Add FlatFile storage support
Add FlatFileDriver
Lock meta file before reading and writing
use composer cache
add __toString to queue interface
Merge pull request #91 from henrikbjorn/master

add __toString to queue interface
Merge pull request #87 from Baachi/flat-file-storage

Flat file storage
Move documentation into directory as it will be the same as the version and not seperately updated
fix issues for rtfd