Feature/foreground loop fixes Issue #66

I have added 'loop' command in --daemon option which run daemon in foreground, this simple change enable us to run dynamic-dynamodb with supervisord. 

for ex.

dynamic-dynamodb -c example.conf --instance example --daemon loop

sample supervisor conf

[program:example]
command=/usr/local/bin/dynamic-dynamodb -c /path/to/example.conf --instance example --daemon loop
autostart=true
autorestart=true
startsecs=10
redirect_stderr=true