Do further modularization on reporters
Introduce inheritable attributes via Observed::Configurable and refactor the built-in plugins "file" and "stdout" using them.
Configure the logger used by each plugin and stop plugins from spamming debug logs
Correct the code in @example
Merge commit '08014cc2903354816889668e201ad226010fbf51' into develop
Run integration tests on Travis CI
Add an experimental integration Observed with EventMachine
Update gemspec for observed-eventmachine to build the gem
Add an example code to show concurrency achieved by using observed-eventmachine
Inherit attributes configured using Observed::Configurable to sub classes
Give each reporter a reference to the system to allow forwarding reports to other reporters
Merge branch 'em-integration' into develop
Merge branch 'inherit-attributes-to-subclass' into develop
Merge branch 'give-reporter-a-system' into develop
Fix integration tests to include tests for observed plugins and observed integrations
Introduce the default logger for Observed system whose level is not DEBUG but INFO
Fix the bug that the dsl and the builder was not using the default logger
Merge branch 'default-logger-for-system' into develop
Add comments on Configurable, Context, Pluggable
Specify Gemfile used for each bundle command via an environment variable

Conflicts:
	run-integration-tests