MRI errors second try

[jsaak]

After my first attempt to format log exceptions, i found out that there are four places in goliath where it should be used. So i added a log_exception(e) conveninece method to env. And modified all four places to use it. As a bonus the user can use it too.

[igrigorik]

Consistent log_exception makes sense, but I'm not sure we need to (or should even) expose it to the user -- this is internal plumbing.. and they have direct access to the logger anyway?

[jsaak]

if you know a better place to put it, i do not mind moving it

btw, i feel this is mainly log4r territory, and they support this with %M in the PatternFormatter
which uses this function to format all error messages:
https://github.com/colbygk/log4r/blob/master/lib/log4r/formatter/formatter.rb#L70

i just did not want to slow down logging
(and i do not like their exception formatting, but thats another story)