Merge tag 'v1.4.4'

1.4.4
Fix the bad usage of for-in loop against array
Add contribution guidelines

Uses https://cla.strongloop.com
Fix the test cases

See https://github.com/strongloop/loopback-datasource-juggler/pull/296
Merge pull request #59 from strongloop/feature/default-scope

Fix the test cases
fix misspelled attribute "unique" in /lib/mongodb.js
Merge pull request #61 from kaizhu256/master

fix misspelled attribute "unique" in /lib/mongodb.js
Bump version
Merge branch 'release/1.4.5' into production