couch_log: use lager

With this change instead to use our own way to log file we are using
lager which improve the logging which will make couchdb more tolerant in
the face of large or many log messages, won't out of memory the node.

Note: Lager can handle multiple backend butwe are for now only handling
the file and console backend in the ini file. Other backends can be
configured using the app.config file.
couch_log: be less invasive when using parse_transform

Noticed when running tests vi travis-ci, jiffy doesn't like too much
lager and the build hangs. So instead to compile all modules with the
parse transform, only do it for couch_log. This is the only place where
we really need it anyway.