go-url-shortener-app.conf.erb: add db.maxidle property
reduce maxidle to 10
remove maxidle
Revert "nginx.rb: set keep alive timeout to 15"

This reverts commit 7e8e4e43b82e6ee395f26c1db9bf8fbc81afe579.
Revert "remove maxidle"

This reverts commit 5035f195410179ab63f553a4af00b24534192288.
- increase mysql pool size to 200
- add redis pool size (50)
nginx.rb: turn off tcp_tw_recycle
benchmark.rb: various tweaks
limit maxidle to 50
mysql.rb: not sure why i was raising nginx user limit in the mysql role (typo ?)
mysql.rb: increase innodb buffer pool size to 8G
mysql.rb: max_connections 2000, thread_cache_size: 200