Fix minor bug in example

Error callback in shell example needs to be passed the error :-)
Merge pull request #16 from brockgr/master

Minor doc typo
improve specs, add a way to load to environment variables to parametrize tests (and defer to hardcoded values if necessary)

fixed with feedback
fixes !ruby-1.9.2 compatibility

https://github.com/rspec/rspec-core/issues/506
http://bugs.ruby-lang.org/issues/5657
test constants look more like constants
Merge branch 'freakhill-slightly-better-specs' into 0.4

Conflicts:
	spec/em-ssh_spec.rb