Improve pid and log files settings

* the pid file has its increment before the extension when processes > 1
* the log file can be configured.
* the environment is inferred.

Inspired from https://github.com/mperham/sidekiq/pull/1539
pid file increment for all instances

When processes > 1, all pid files have an increment,
not just those after the first.
Add the loading block back
Revert "pid file increment for all instances"

Extracted in https://github.com/seuros/capistrano-sidekiq/pull/2
This reverts commit d34374ab756b51f5d98edc8bf009391367b8b665.
Merge pull request #1 from jlecour/pr-1

Improve pid and log files settings