Try to get configuration from the name or camlized version of the name.

In some place we document that an engine name can be all lower cases, or
uppercase, or camelized. In order to make this works, when looking for a
configuration key, we try both the name given to us from the config, or the
camelized name.
Drop support for log_path in Dancer2::Logger::File.

The log_path option was available as a backward compatibility feature
in Dancer1, but there's no need to cary this one over Dancer2.

This change remove the mention of log_file and log_path from the documentation,
and makes the default location for the log file (if none specified) to be the
application's directory.
Move the POD at the bottom of Dancer2::Logger::File
Update changes
Merge branch 'devel' into tests/log-path
Merge branch 'tests/log-path' into devel