Switch out MetricFu.configuration.mf_debug for MetricFu.logger.mf_debug

Fixes calls to private method in
https://travis-ci.org/metricfu/metric_fu/builds/23890389
Move Template into templates directory
Rename all metric template files report.html.erb
Centralize templates, rename and namespace AwesomeTemplate

AwesomeTemplate -> MetricFu::Templates::MetricsTemplate
Document render_partial method
Consolidate graphing code
Put generators in lib
Add general MetricFu::Errors error base class
MetricFu should know its URL, not a template