test: increase timeout for `npm install`
facet: use a static version of getUniqueId

Remove an unnecessary call of `new ModelDefinition`, pass the definition
data directly to `ModelDefinition.getUniqueId`.
Definition.addToCache: remove related models

When adding a definition to datasource cache, data of the related models
embedded in the configuration must be removed.

See strongloop/loopback-datasource-juggler#242
WorkspaceEntity.getFromCache: improve error msg

Catch JSON syntax errors and add model name & id to the error message
thrown.
Merge pull request #114 from strongloop/feature/fix-ci-build

fix CI build