Catch method invocation error to avoid crashing

See https://github.com/strongloop/loopback-connector-postgresql/issues/37
Merge pull request #119 from strongloop/feature/catch-method-error

Catch method invocation error to avoid crashing
Bump version
Merge branch 'release/2.7.1' into production
Merge tag 'v2.7.1'

2.7.1