Migrate tests to Mocha framework

- expresso is deprecated
- migrate tests to mocha
- drop database between it 'blocks'
- bump mongoose dependency to >=3.0.0
- add devDependencies to mocha & should

closes #1
Merge branch 'master' into js-predictable-relationships

Conflicts:
	package.json
	specs/belongsTo.spec.js
	specs/hasMany.spec.js
	test/common.js